Air and Weather

Best 100 Air and Weather Books, eBooks, Information, Products and Services
plus lots of Promotional Contents, Free for all Visitors

This site is Under Development, Coming Soon?


Temperature: The Driving Force | Richard Hammond’s: Wild Weather | Spark
Richard Hammond investigates the crucial role temperature plays in all weather. Without heat, there would be no weather – no clouds, no rain, no snow, no dust storms, no thunder and lightning.
Wind: The Invisible Force | Richard Hammond’s: Wild Weather | Spark
Richard Hammond investigates how wind actually starts. He visits one of the windiest places on the planet, walks into the centre of a man-made tornado and creates a 10-metre high whirlwind – made of fire!


Breath: The New Science of a Lost Art
Breath: The New Science of a Lost Ar Audible Audiobook – Unabridged

James Nestor (Author, Narrator), Penguin Audio (Publisher) Paperback $12.49 Kindle $9.99


The Healing Power of the Breath: Simple Techniques to Reduce Stress and Anxiety, Enhance Concentration, and Balance Your Emotions

The Healing Power of the Breath:

Simple Techniques to Reduce Stress and Anxiety, Enhance Concentration, and Balance Your Emotions Paperback and Kindel $12.49

A drug-free, side effect-free solution to common stress and mood problems—developed by two physicians
Millions of Americans suffer from mood problems and stress-related issues like anxiety, depression, insomnia, and PTSD. Far too many of them are taking medications that have troublesome side effects, withdrawal symptoms, and disappointing success rates.


Just Breathe: Mastering Breathwork

Just Breathe: Mastering Breathwork Paperback – 2018

by Dan Brule  (Author), Tony Robbins (Foreword) Paperback 14.49 Kindel $12.99

Hailed by Tony Robbins as the “definitive breathwork handbook,” Just Breathe will teach you how to harness your breath to reduce stress, increase productivity, balance your health, and find the path to spiritual awakening.

Big meeting jitters? Anxiety over a test or taxes? Hard time focusing? What if you could control your outcomes and change results simply by regulating your breath?

In this simple and revolutionary guide, world-renowned pioneer of breathwork Dan Brulé shares the Breath Mastery technique that has helped people in more than fifty countries reduce anxiety, improve their health, and tap infinite stores of energy. Just Breathe reveals the truth that elite athletes, champion martial artists, Navy SEAL warriors, first responders, and spiritual yogis have always known—when you regulate your breathing, you can moderate your state of well-being. So if you want to clear and calm your mind and spark peak performance, the secret is just a breath away.

Breathwork gives you the tools to achieve benefits in a wide range of issues including: managing acute/chronic pain; helping with insomnia, weight loss, attention deficit, anxiety, depression, trauma, and grief; improving intuition, creativity, mindfulness, self-esteem, and leadership; and much more. Recommended “for those who wish to destress naturally” (Library Journal), Just Breathe will help you utilize your breath to benefit your body, mind, and spirit.


Science of Breath

Science of Breath 2019 Paperback $8.99

The Western student is apt to be somewhat confused in his ideas regarding the Yogis and their philosophy and practice. Travelers to India have written great tales about the hordes of fakirs, mendicants and mountebanks who infest the great roads of India and the streets of its cities, and who impudently claim the title “Yogi.”


Laughter Yoga: Daily Practices for Health and Happiness
Laughter Yoga: Daily Practices for Health and Happiness 
Paperback – 2020

by Madan Kataria M.D. (Author), Andrew Weil M.D. (Foreword)

Paperback $13.58 Kindle from $11.99


Breathe Paperback – December 27, 2016

by Belisa Vranich (Author) Kindle from $9.99 Paperback $18.99 

Insomnia? Gone. Anxiety? Gone. All without medication. Unpleasant side effects from blood pressure pills? Gone. A cheap and effective way to combat cardiovascular disease, immune dysfunction, obesity, and GI disorders? Yes. Sounds too good to be true? Believe it.

Contemporary science confirms what generations of healers have observed through centuries of practice: Breath awareness can turn on the body’s natural abilities to prevent and cure illness. The mental and physical stresses of modern life, such as anxiety, frustration, sexual dysfunction, insomnia, high blood pressure, digestive woes, and immune dysfunction can all be addressed through conscious control of your breath. In addition, it can increase energy, accelerate healing, improve cognitive skills, and enhance mental balance.


Air or Weather

By vol­ume, dry air con­tains 78.09% ni­tro­gen, 20.95% oxy­gen, 0.93% argon, 0.04% car­bon diox­ide, and small amounts of other gases.[8] Air also con­tains a vari­able amount of water vapor, on av­er­age around 1% at sea level, and 0.4% over the en­tire at­mos­phere. Air com­po­si­tion, tem­per­a­ture, and at­mos­pheric pres­sure vary with al­ti­tude, and air suit­able for use in pho­to­syn­the­sis by ter­res­trial plants and breath­ing of ter­res­trial an­i­mals is found only in Earth’s tro­pos­phere and in ar­ti­fi­cial at­mos­pheres.

Air or Atmosphere of Earth

From Wikipedia, the free encyclopedia
NASA photo showing Earth's atmosphere at sunset, with Earth silhouetted

NASA photo showing Earth’s atmosphere at sunset, with Earth silhouetted

Blue light is scattered more than other wavelengths by the gases in the atmosphere, surrounding Earth in a visibly blue layer when seen from space onboard the ISS at an altitude of 335 km (208 mi).[1]

Blue light is scattered more than other wavelengths by the gases in the atmosphere, surrounding Earth in a visibly blue layer when seen from space onboard the ISS at an altitude of 335 km (208 mi).Composition of Earth’s atmosphere by volume, excluding water vapor. Lower pie represents trace gases that together compose about 0.043391% of the atmosphere (0.04402961% at April 2019 concentration ). Numbers are mainly from 2000, with CO
2 and methane from 2019, and do not represent any single source.

The at­mos­phere of Earth is the layer of gases, com­monly known as air, re­tained by Earth’s grav­ity, sur­round­ing the planet Earth and form­ing its plan­e­tary at­mos­phere. The at­mos­phere of Earth pro­tects life on Earth by cre­at­ing pres­sure al­low­ing for liq­uid water to exist on the Earth’s sur­face, ab­sorb­ing ul­tra­vi­o­let solar ra­di­a­tion, warm­ing the sur­face through heat re­ten­tion (green­house ef­fect), and re­duc­ing tem­per­a­ture ex­tremes be­tween day and night (the di­ur­nal tem­per­a­ture vari­a­tion).

By vol­ume, dry air con­tains 78.09% ni­tro­gen, 20.95% oxy­gen, 0.93% argon, 0.04% car­bon diox­ide, and small amounts of other gases.[8] Air also con­tains a vari­able amount of water vapor, on av­er­age around 1% at sea level, and 0.4% over the en­tire at­mos­phere. Air com­po­si­tion, tem­per­a­ture, and at­mos­pheric pres­sure vary with al­ti­tude, and air suit­able for use in pho­to­syn­the­sis by ter­res­trial plants and breath­ing of ter­res­trial an­i­mals is found only in Earth’s tro­pos­phere and in ar­ti­fi­cial at­mos­pheres.

Earth’s at­mos­phere has changed much since it’s for­ma­tion as pri­mar­ily a hy­dro­gen at­mos­phere, and has changed dra­mat­i­cally on sev­eral oc­ca­sions — for ex­am­ple, the Great Ox­i­da­tion Event 2.4 bil­lion years ago, greatly in­creased oxy­gen in the at­mos­phere from prac­ti­cally no oxy­gen to lev­els closer to pre­sent day. Hu­mans have also con­tributed to sig­nif­i­cant changes in at­mos­pheric com­po­si­tion through air po­lu­tion, es­pe­cially since in­dus­tri­al­i­sa­tion, lead­ing to rapid en­vi­ron­men­tal change such as ozone de­ple­tion and global warm­ing.

The at­mos­phere has a mass of about 5.15×1018 kg,[9] three quar­ters of which is within about 11 km (6.8 mi; 36,000 ft) of the sur­face. The at­mos­phere be­comes thin­ner and thin­ner with in­creas­ing al­ti­tude, with no def­i­nite bound­ary be­tween the at­mos­phere and outer space. The Kármán line, at 100 km (62 mi), or 1.57% of Earth’s ra­dius, is often used as the bor­der be­tween the at­mos­phere and outer space. At­mos­pheric ef­fects be­come no­tice­able dur­ing at­mos­pheric reen­try of space­craft at an al­ti­tude of around 120 km (75 mi). Sev­eral lay­ers can be dis­tin­guished in the at­mos­phere, based on char­ac­ter­is­tics such as tem­per­a­ture and com­po­si­tion.

The study of Earth’s at­mos­phere and its processes is called at­mos­pheric sci­ence (aerol­ogy), and in­cludes mul­ti­ple sub­fields, such as cli­ma­tol­ogy and at­mos­pheric physics. Early pi­o­neers in the field in­clude Léon Teis­serenc de Bort and Richard Ass­mann.[10] The study of his­toric at­mos­phere is called pa­le­o­cli­ma­tol­ogy.


YouTube Encyclopedic 

  • 1/5Views:393 412
  • ✪ The Atmosphere
  • ✪ 25 Facts About Earth’s Atmosphere That Are Truly Majestic
  • ✪ Learn About Planet Earth – Earth’s Atmosphere
  • ✪ National Geographic Our Atmosphere Earth Science
  • ✪ Layers Of Atmosphere | The Dr. Binocs Show | Educational Videos For Kids


Main article: Atmospheric chemistry

Mean atmospheric water vapor

Mean atmospheric water vapor

The three major con­stituents of Earth’s at­mos­phere are ni­tro­genoxy­gen, and argon. Water vapor ac­counts for roughly 0.25% of the at­mos­phere by mass. The con­cen­tra­tion of water vapor (a green­house gas) varies sig­nif­i­cantly from around 10 ppm by vol­ume in the cold­est por­tions of the at­mos­phere to as much as 5% by vol­ume in hot, humid air masses, and con­cen­tra­tions of other at­mos­pheric gases are typ­i­cally quoted in terms of dry air (with­out water vapor).[11] The re­main­ing gases are often re­ferred to as trace gases,[12] among which are the green­house gases, prin­ci­pally car­bon diox­ide, methane, ni­trous oxide, and ozone. Be­sides argon, al­ready men­tioned, other noble gases, neon, he­lium, kryp­ton, and xenon are also pre­sent. Fil­tered air in­cludes trace amounts of many other chem­i­cal com­pounds. Many sub­stances of nat­ural ori­gin may be pre­sent in lo­cally and sea­son­ally vari­able small amounts as aerosols in an un­fil­tered air sam­ple, in­clud­ing dust of min­eral and or­ganic com­po­si­tion, pollen and sporessea spray, and vol­canic ash. Var­i­ous in­dus­trial pol­lu­tants also may be pre­sent as gases or aerosols, such as chlo­rine (el­e­men­tal or in com­pounds), flu­o­rine com­pounds and el­e­men­tal mer­cury vapor. Sul­fur com­pounds such as hy­dro­gen sul­fide and sul­fur diox­ide (SO2) may be de­rived from nat­ural sources or from in­dus­trial air pol­lu­tion.

NameFormulain ppmv(B)in %
Carbon dioxide
(April, 2020)(C)[13]
Not included in above dry atmosphere:
Water vapor(D)H2O0–30,000(D)0–3%(E)
(A) vol­ume frac­tion is equal to mole frac­tion for ideal gas only,
    also see vol­ume (ther­mo­dy­nam­ics)
(B) ppmv: parts per mil­lion by vol­ume
(C) The con­cen­tra­tion of CO
2 has been in­creas­ing in re­cent decades
(D) Water vapor is about 0.25% by mass over full atmosphere
(E) Water vapor strongly varies locally[11]

The av­er­age mol­e­c­u­lar weight of dry air, which can be used to cal­cu­late den­si­ties or to con­vert be­tween mole frac­tion and mass frac­tion, is about 28.946[14] or 28.96[15] g/mol. This is de­creased when the air is humid.

The rel­a­tive con­cen­tra­tion of gases re­mains con­stant until about 10,000 m (33,000 ft).[16]The volume fraction of the main constituents of the Earth’s atmosphere as a function of height according to the MSIS-E-90 atmospheric model.


Earth’s atmosphere Lower 4 layers of the atmosphere in 3 dimensions as seen diagonally from above the exobase. Layers drawn to scale, objects within the layers are not to scale. Aurorae shown here at the bottom of the thermosphere can actually form at any altitude in this atmospheric layer.

In gen­eral, air pres­sure and den­sity de­crease with al­ti­tude in the at­mos­phere. How­ever, tem­per­a­ture has a more com­pli­cated pro­file with al­ti­tude, and may re­main rel­a­tively con­stant or even in­crease with al­ti­tude in some re­gions (see the tem­per­a­ture sec­tion, below). Be­cause the gen­eral pat­tern of the tem­per­a­ture/al­ti­tude pro­file, or lapse rate, is con­stant and mea­sur­able by means of in­stru­mented bal­loon sound­ings, the tem­per­a­ture be­hav­ior pro­vides a use­ful met­ric to dis­tin­guish at­mos­pheric lay­ers. In this way, Earth’s at­mos­phere can be di­vided (called at­mos­pheric strat­i­fi­ca­tion) into five main lay­ers. Ex­clud­ing the ex­os­phere, the at­mos­phere has four pri­mary lay­ers, which are the tro­pos­phere, stratos­phere, mesos­phere, and thermosphere.[17] From high­est to low­est, the five main lay­ers are:

  • Exosphere: 700 to 10,000 km (440 to 6,200 miles)
  • Thermosphere: 80 to 700 km (50 to 440 miles)[18]
  • Mesosphere: 50 to 80 km (31 to 50 miles)
  • Stratosphere: 12 to 50 km (7 to 31 miles)
  • Troposphere: 0 to 12 km (0 to 7 miles)[19]


Main article: Exosphere

The ex­os­phere is the out­er­most layer of Earth’s at­mos­phere (i.e. the upper limit of the at­mos­phere). It ex­tends from the exobase, which is lo­cated at the top of the ther­mos­phere at an al­ti­tude of about 700 km above sea level, to about 10,000 km (6,200 mi; 33,000,000 ft) where it merges into the solar wind.

This layer is mainly com­posed of ex­tremely low den­si­ties of hy­dro­gen, he­lium and sev­eral heav­ier mol­e­cules in­clud­ing ni­tro­gen, oxy­gen and car­bon diox­ide closer to the exobase. The atoms and mol­e­cules are so far apart that they can travel hun­dreds of kilo­me­ters with­out col­lid­ing with one an­other. Thus, the ex­os­phere no longer be­haves like a gas, and the par­ti­cles con­stantly es­cape into space. These free-mov­ing par­ti­cles fol­low bal­lis­tic tra­jec­to­ries and may mi­grate in and out of the mag­ne­tos­phere or the solar wind.

The ex­os­phere is lo­cated too far above Earth for any me­te­o­ro­log­i­cal phe­nom­ena to be pos­si­ble. How­ever, the au­rora bo­re­alis and au­rora aus­tralis some­times occur in the lower part of the ex­os­phere, where they over­lap into the ther­mos­phere. The ex­os­phere con­tains most of the satel­lites or­bit­ing Earth.


Main article: Thermosphere

The ther­mos­phere is the sec­ond-high­est layer of Earth’s at­mos­phere. It ex­tends from the mesopause (which sep­a­rates it from the mesos­phere) at an al­ti­tude of about 80 km (50 mi; 260,000 ft) up to the ther­mopause at an al­ti­tude range of 500–1000 km (310–620 mi; 1,600,000–3,300,000 ft). The height of the ther­mopause varies con­sid­er­ably due to changes in solar activity.[18] Be­cause the ther­mopause lies at the lower bound­ary of the ex­os­phere, it is also re­ferred to as the exobase. The lower part of the ther­mos­phere, from 80 to 550 kilo­me­tres (50 to 342 mi) above Earth’s sur­face, con­tains the ionos­phere.

The tem­per­a­ture of the ther­mos­phere grad­u­ally in­creases with height. Un­like the stratos­phere be­neath it, wherein a tem­per­a­ture in­ver­sion is due to the ab­sorp­tion of ra­di­a­tion by ozone, the in­ver­sion in the ther­mos­phere oc­curs due to the ex­tremely low den­sity of its mol­e­cules. The tem­per­a­ture of this layer can rise as high as 1500 °C (2700 °F), though the gas mol­e­cules are so far apart that its tem­per­a­ture in the usual sense is not very mean­ing­ful. The air is so rar­efied that an in­di­vid­ual mol­e­cule (of oxy­gen, for ex­am­ple) trav­els an av­er­age of 1 kilo­me­tre (0.62 mi; 3300 ft) be­tween col­li­sions with other molecules.[20] Al­though the ther­mos­phere has a high pro­por­tion of mol­e­cules with high en­ergy, it would not feel hot to a human in di­rect con­tact, be­cause its den­sity is too low to con­duct a sig­nif­i­cant amount of en­ergy to or from the skin.

This layer is com­pletely cloud­less and free of water vapor. How­ever, non-hy­drom­e­te­o­ro­log­i­cal phe­nom­ena such as the au­rora bo­re­alis and au­rora aus­tralis are oc­ca­sion­ally seen in the ther­mos­phere. The In­ter­na­tional Space Sta­tion or­bits in this layer, be­tween 350 and 420 km (220 and 260 mi).


Main article: Mesosphere

The mesos­phere is the third high­est layer of Earth’s at­mos­phere, oc­cu­py­ing the re­gion above the stratos­phere and below the ther­mos­phere. It ex­tends from the stratopause at an al­ti­tude of about 50 km (31 mi; 160,000 ft) to the mesopause at 80–85 km (50–53 mi; 260,000–280,000 ft) above sea level.

Tem­per­a­tures drop with in­creas­ing al­ti­tude to the mesopause that marks the top of this mid­dle layer of the at­mos­phere. It is the cold­est place on Earth and has an av­er­age tem­per­a­ture around −85 °C (−120 °F; 190 K).[21][22]

Just below the mesopause, the air is so cold that even the very scarce water vapor at this al­ti­tude can be sub­li­mated into po­lar-mesos­pheric noc­tilu­cent clouds. These are the high­est clouds in the at­mos­phere and may be vis­i­ble to the naked eye if sun­light re­flects off them about an hour or two after sun­set or a sim­i­lar length of time be­fore sun­rise. They are most read­ily vis­i­ble when the Sun is around 4 to 16 de­grees below the hori­zon. Light­ning-in­duced dis­charges known as tran­sient lu­mi­nous events (TLEs) oc­ca­sion­ally form in the mesos­phere above tro­pos­pheric thun­der­clouds. The mesos­phere is also the layer where most me­te­ors burn up upon at­mos­pheric en­trance. It is too high above Earth to be ac­ces­si­ble to jet-pow­ered air­craft and bal­loons, and too low to per­mit or­bital space­craft. The mesos­phere is mainly ac­cessed by sound­ing rock­ets and rocket-pow­ered air­craft.


Main article: Stratosphere

The stratos­phere is the sec­ond-low­est layer of Earth’s at­mos­phere. It lies above the tro­pos­phere and is sep­a­rated from it by the tropopause. This layer ex­tends from the top of the tro­pos­phere at roughly 12 km (7.5 mi; 39,000 ft) above Earth’s sur­face to the stratopause at an al­ti­tude of about 50 to 55 km (31 to 34 mi; 164,000 to 180,000 ft).

The at­mos­pheric pres­sure at the top of the stratos­phere is roughly 1/1000 the pres­sure at sea level. It con­tains the ozone layer, which is the part of Earth’s at­mos­phere that con­tains rel­a­tively high con­cen­tra­tions of that gas. The stratos­phere de­fines a layer in which tem­per­a­tures rise with in­creas­ing al­ti­tude. This rise in tem­per­a­ture is caused by the ab­sorp­tion of ul­tra­vi­o­let ra­di­a­tion (UV) ra­di­a­tion from the Sun by the ozone layer, which re­stricts tur­bu­lence and mix­ing. Al­though the tem­per­a­ture may be −60 °C (−76 °F; 210 K) at the tropopause, the top of the stratos­phere is much warmer, and may be near 0 °C.[23]

The stratos­pheric tem­per­a­ture pro­file cre­ates very sta­ble at­mos­pheric con­di­tions, so the stratos­phere lacks the weather-pro­duc­ing air tur­bu­lence that is so preva­lent in the tro­pos­phere. Con­se­quently, the stratos­phere is al­most com­pletely free of clouds and other forms of weather. How­ever, polar stratos­pheric or nacre­ous clouds are oc­ca­sion­ally seen in the lower part of this layer of the at­mos­phere where the air is cold­est. The stratos­phere is the high­est layer that can be ac­cessed by jet-pow­ered air­craft.


Main article: Troposphere

The tro­pos­phere is the low­est layer of Earth’s at­mos­phere. It ex­tends from Earth’s sur­face to an av­er­age height of about 12 km (7.5 mi; 39,000 ft), al­though this al­ti­tude varies from about 9 km (5.6 mi; 30,000 ft) at the ge­o­graphic poles to 17 km (11 mi; 56,000 ft) at the Equa­tor,[19] with some vari­a­tion due to weather. The tro­pos­phere is bounded above by the tropopause, a bound­ary marked in most places by a tem­per­a­ture in­ver­sion (i.e. a layer of rel­a­tively warm air above a colder one), and in oth­ers by a zone which is isother­mal with height.[24][25]

Al­though vari­a­tions do occur, the tem­per­a­ture usu­ally de­clines with in­creas­ing al­ti­tude in the tro­pos­phere be­cause the tro­pos­phere is mostly heated through en­ergy trans­fer from the sur­face. Thus, the low­est part of the tro­pos­phere (i.e. Earth’s sur­face) is typ­i­cally the warmest sec­tion of the tro­pos­phere. This pro­motes ver­ti­cal mix­ing (hence, the ori­gin of its name in the Greek word τρόπος, tro­pos, mean­ing “turn”). The tro­pos­phere con­tains roughly 80% of the mass of Earth’s atmosphere.[26] The tro­pos­phere is denser than all its over­ly­ing at­mos­pheric lay­ers be­cause a larger at­mos­pheric weight sits on top of the tro­pos­phere and causes it to be most se­verely com­pressed. Fifty per­cent of the total mass of the at­mos­phere is lo­cated in the lower 5.6 km (3.5 mi; 18,000 ft) of the tro­pos­phere.

Nearly all at­mos­pheric water vapor or mois­ture is found in the tro­pos­phere, so it is the layer where most of Earth’s weather takes place. It has ba­si­cally all the weather-as­so­ci­ated cloud genus types gen­er­ated by ac­tive wind cir­cu­la­tion, al­though very tall cu­mu­lonim­bus thun­der clouds can pen­e­trate the tropopause from below and rise into the lower part of the stratos­phere. Most con­ven­tional avi­a­tion ac­tiv­ity takes place in the tro­pos­phere, and it is the only layer that can be ac­cessed by pro­peller-dri­ven air­craft.

Space Shuttle Endeavour orbiting in the thermosphere. Because of the angle of the photo, it appears to straddle the stratosphere and mesosphere that actually lie more than 250 km (160 mi) below. The orange layer is the troposphere, which gives way to the whitish stratosphere and then the blue mesosphere.[27]

Space ShuttleEndeavour orbiting in the thermosphere. Because of the angle of the photo, it appears to straddle the stratosphere and mesosphere that actually lie more than 250 km (160 mi) below. The orange layer is the troposphere, which gives way to the whitish stratosphere and then the blue mesosphere.[27]

Other layers

Within the five prin­ci­pal lay­ers above, that are largely de­ter­mined by tem­per­a­ture, sev­eral sec­ondary lay­ers may be dis­tin­guished by other prop­er­ties:

  • The ozone layer is contained within the stratosphere. In this layer ozone concentrations are about 2 to 8 parts per million, which is much higher than in the lower atmosphere but still very small compared to the main components of the atmosphere. It is mainly located in the lower portion of the stratosphere from about 15–35 km (9.3–21.7 mi; 49,000–115,000 ft), though the thickness varies seasonally and geographically. About 90% of the ozone in Earth’s atmosphere is contained in the stratosphere.
  • The ionosphere is a region of the atmosphere that is ionized by solar radiation. It is responsible for auroras. During daytime hours, it stretches from 50 to 1,000 km (31 to 621 mi; 160,000 to 3,280,000 ft) and includes the mesosphere, thermosphere, and parts of the exosphere. However, ionization in the mesosphere largely ceases during the night, so auroras are normally seen only in the thermosphere and lower exosphere. The ionosphere forms the inner edge of the magnetosphere. It has practical importance because it influences, for example, radio propagation on Earth.
  • The homosphere and heterosphere are defined by whether the atmospheric gases are well mixed. The surface-based homosphere includes the troposphere, stratosphere, mesosphere, and the lowest part of the thermosphere, where the chemical composition of the atmosphere does not depend on molecular weight because the gases are mixed by turbulence.[28] This relatively homogeneous layer ends at the turbopause found at about 100 km (62 mi; 330,000 ft), the very edge of space itself as accepted by the FAI, which places it about 20 km (12 mi; 66,000 ft) above the mesopause.

Above this altitude lies the heterosphere, which includes the exosphere and most of the thermosphere. Here, the chemical composition varies with altitude. This is because the distance that particles can move without colliding with one another is large compared with the size of motions that cause mixing. This allows the gases to stratify by molecular weight, with the heavier ones, such as oxygen and nitrogen, present only near the bottom of the heterosphere. The upper part of the heterosphere is composed almost completely of hydrogen, the lightest element.

  • The planetary boundary layer is the part of the troposphere that is closest to Earth’s surface and is directly affected by it, mainly through turbulent diffusion. During the day the planetary boundary layer usually is well-mixed, whereas at night it becomes stably stratified with weak or intermittent mixing. The depth of the planetary boundary layer ranges from as little as about 100 metres (330 ft) on clear, calm nights to 3,000 m (9,800 ft) or more during the afternoon in dry regions.

The av­er­age tem­per­a­ture of the at­mos­phere at Earth’s sur­face is 14 °C (57 °F; 287 K)[29] or 15 °C (59 °F; 288 K),[30] de­pend­ing on the reference.[31][32][33]

Physical properties

Comparison of the 1962 US Standard Atmosphere graph of geometric altitude against air densitypressure, the speed of sound and temperature with approximate altitudes of various objects.[34]

Pressure and thickness

Main article: Atmospheric pressure

The av­er­age at­mos­pheric pres­sure at sea level is de­fined by the In­ter­na­tional Stan­dard At­mos­phere as 101325 pas­cals (760.00 Torr; 14.6959 psi; 760.00 mmHg). This is some­times re­ferred to as a unit of stan­dard at­mos­pheres (atm). Total at­mos­pheric mass is 5.1480×1018 kg (1.135×1019 lb),[35] about 2.5% less than would be in­ferred from the av­er­age sea level pres­sure and Earth’s area of 51007.2 mega­hectares, this por­tion being dis­placed by Earth’s moun­tain­ous ter­rain. At­mos­pheric pres­sure is the total weight of the air above unit area at the point where the pres­sure is mea­sured. Thus air pres­sure varies with lo­ca­tion and weather.

If the en­tire mass of the at­mos­phere had a uni­form den­sity equal to sea level den­sity (about 1.2 kg per m3) from sea level up­wards, it would ter­mi­nate abruptly at an al­ti­tude of 8.50 km (27,900 ft). It ac­tu­ally de­creases ex­po­nen­tially with al­ti­tude, drop­ping by half every 5.6 km (18,000 ft) or by a fac­tor of 1/e every 7.64 km (25,100 ft), the av­er­age scale height of the at­mos­phere below 70 km (43 mi; 230,000 ft). How­ever, the at­mos­phere is more ac­cu­rately mod­eled with a cus­tomized equa­tion for each layer that takes gra­di­ents of tem­per­a­ture, mol­e­c­u­lar com­po­si­tion, solar ra­di­a­tion and grav­ity into ac­count.

In sum­mary, the mass of Earth’s at­mos­phere is dis­trib­uted ap­prox­i­mately as follows:[36]

  • 50% is below 5.6 km (18,000 ft).
  • 90% is below 16 km (52,000 ft).
  • 99.99997% is below 100 km (62 mi; 330,000 ft), the Kármán line. By international convention, this marks the beginning of space where human travelers are considered astronauts.

By com­par­i­son, the sum­mit of Mt. Ever­est is at 8,848 m (29,029 ft); com­mer­cial air­lin­ers typ­i­cally cruise be­tween 10 and 13 km (33,000 and 43,000 ft) where the thin­ner air im­proves fuel econ­omy; weather bal­loons reach 30.4 km (100,000 ft) and above; and the high­est X-15 flight in 1963 reached 108.0 km (354,300 ft).

Even above the Kármán line, sig­nif­i­cant at­mos­pheric ef­fects such as au­ro­ras still occur. Me­te­ors begin to glow in this re­gion, though the larger ones may not burn up until they pen­e­trate more deeply. The var­i­ous lay­ers of Earth’s ionos­phere, im­por­tant to HF radio prop­a­ga­tion, begin below 100 km and ex­tend be­yond 500 km. By com­par­i­son, the In­ter­na­tional Space Sta­tion and Space Shut­tle typ­i­cally orbit at 350–400 km, within the F-layer of the ionos­phere where they en­counter enough at­mos­pheric drag to re­quire re­boosts every few months. De­pend­ing on solar ac­tiv­ity, satel­lites can ex­pe­ri­ence no­tice­able at­mos­pheric drag at al­ti­tudes as high as 700–800 km.

Temperature and speed of sound

Main articles: Atmospheric temperature and Speed of sound

Temperature trends in two thick layers of the atmosphere as measured between January 1979 and December 2005 by Microwave Sounding Units and Advanced Microwave Sounding Units on NOAA weather satellites.  The instruments record microwaves emitted from oxygen molecules in the atmosphere. Source:[37]

Temperature trends in two thick layers of the atmosphere as measured between January 1979 and December 2005 by Microwave Sounding Units and Advanced Microwave Sounding Units on NOAA weather satellites. The instruments record microwaves emitted from oxygen molecules in the atmosphere. Source:[37]

The di­vi­sion of the at­mos­phere into lay­ers mostly by ref­er­ence to tem­per­a­ture is dis­cussed above. Tem­per­a­ture de­creases with al­ti­tude start­ing at sea level, but vari­a­tions in this trend begin above 11 km, where the tem­per­a­ture sta­bi­lizes through a large ver­ti­cal dis­tance through the rest of the tro­pos­phere. In the stratos­phere, start­ing above about 20 km, the tem­per­a­ture in­creases with height, due to heat­ing within the ozone layer caused by cap­ture of sig­nif­i­cant ul­tra­vi­o­let ra­di­a­tion from the Sun by the dioxy­gen and ozone gas in this re­gion. Still an­other re­gion of in­creas­ing tem­per­a­ture with al­ti­tude oc­curs at very high al­ti­tudes, in the aptly-named ther­mos­phere above 90 km.

Be­cause in an ideal gas of con­stant com­po­si­tion the speed of sound de­pends only on tem­per­a­ture and not on the gas pres­sure or den­sity, the speed of sound in the at­mos­phere with al­ti­tude takes on the form of the com­pli­cated tem­per­a­ture pro­file (see il­lus­tra­tion to the right), and does not mir­ror al­ti­tu­di­nal changes in den­sity or pres­sure.

Density and mass

Temperature and mass density against altitude from the NRLMSISE-00 standard atmosphere model (the eight dotted lines in each "decade" are at the eight cubes 8, 27, 64, ..., 729)

Temperature and mass density against altitude from the NRLMSISE-00standard atmosphere model (the eight dotted lines in each “decade” are at the eight cubes 8, 27, 64, …, 729)Main article: Density of air

The den­sity of air at sea level is about 1.2 kg/m3 (1.2 g/L, 0.0012 g/cm3). Den­sity is not mea­sured di­rectly but is cal­cu­lated from mea­sure­ments of tem­per­a­ture, pres­sure and hu­mid­ity using the equa­tion of state for air (a form of the ideal gas law). At­mos­pheric den­sity de­creases as the al­ti­tude in­creases. This vari­a­tion can be ap­prox­i­mately mod­eled using the baro­met­ric for­mula. More so­phis­ti­cated mod­els are used to pre­dict or­bital decay of satel­lites.

The av­er­age mass of the at­mos­phere is about 5 quadrillion (5×1015tonnes or 1/1,200,000 the mass of Earth. Ac­cord­ing to the Amer­i­can Na­tional Cen­ter for At­mos­pheric Re­search, “The total mean mass of the at­mos­phere is 5.1480×1018 kg with an an­nual range due to water vapor of 1.2 or 1.5×1015 kg, de­pend­ing on whether sur­face pres­sure or water vapor data are used; some­what smaller than the pre­vi­ous es­ti­mate. The mean mass of water vapor is es­ti­mated as 1.27×1016 kg and the dry air mass as 5.1352 ±0.0003×1018 kg.”

Optical properties

See also: Sunlight

Solar ra­di­a­tion (or sun­light) is the en­ergy Earth re­ceives from the Sun. Earth also emits ra­di­a­tion back into space, but at longer wave­lengths that we can­not see. Part of the in­com­ing and emit­ted ra­di­a­tion is ab­sorbed or re­flected by the at­mos­phere. In May 2017, glints of light, seen as twin­kling from an or­bit­ing satel­lite a mil­lion miles away, were found to be re­flected light from ice crys­tals in the atmosphere.[38][39]


Main article: Atmospheric scattering

When light passes through Earth’s at­mos­phere, pho­tons in­ter­act with it through scat­ter­ing. If the light does not in­ter­act with the at­mos­phere, it is called di­rect radiation and is what you see if you were to look di­rectly at the Sun. In­di­rect radiation is light that has been scat­tered in the at­mos­phere. For ex­am­ple, on an over­cast day when you can­not see your shadow there is no di­rect ra­di­a­tion reach­ing you, it has all been scat­tered. As an­other ex­am­ple, due to a phe­nom­e­non called Rayleigh scat­ter­ing, shorter (blue) wave­lengths scat­ter more eas­ily than longer (red) wave­lengths. This is why the sky looks blue; you are see­ing scat­tered blue light. This is also why sun­sets are red. Be­cause the Sun is close to the hori­zon, the Sun’s rays pass through more at­mos­phere than nor­mal to reach your eye. Much of the blue light has been scat­tered out, leav­ing the red light in a sun­set.


Main article: Absorption (electromagnetic radiation)Rough plot of Earth’s atmospheric transmittance (or opacity) to various wavelengths of electromagnetic radiation, including visible light.

Dif­fer­ent mol­e­cules ab­sorb dif­fer­ent wave­lengths of ra­di­a­tion. For ex­am­ple, O2 and O3 ab­sorb al­most all wave­lengths shorter than 300 nanome­ters. Water (H2O) ab­sorbs many wave­lengths above 700 nm. When a mol­e­cule ab­sorbs a pho­ton, it in­creases the en­ergy of the mol­e­cule. This heats the at­mos­phere, but the at­mos­phere also cools by emit­ting ra­di­a­tion, as dis­cussed below.

The com­bined ab­sorp­tion spec­tra of the gases in the at­mos­phere leave “win­dows” of low opac­ity, al­low­ing the trans­mis­sion of only cer­tain bands of light. The op­ti­cal win­dow runs from around 300 nm (ul­tra­vi­o­let-C) up into the range hu­mans can see, the vis­i­ble spec­trum (com­monly called light), at roughly 400–700 nm and con­tin­ues to the in­frared to around 1100 nm. There are also in­frared and radio win­dows that trans­mit some in­frared and radio waves at longer wave­lengths. For ex­am­ple, the radio win­dow runs from about one cen­time­ter to about eleven-me­ter waves.


Further information: Emission (electromagnetic radiation)

Emis­sion is the op­po­site of ab­sorp­tion, it is when an ob­ject emits ra­di­a­tion. Ob­jects tend to emit amounts and wave­lengths of ra­di­a­tion de­pend­ing on their “black body” emis­sion curves, there­fore hot­ter ob­jects tend to emit more ra­di­a­tion, with shorter wave­lengths. Colder ob­jects emit less ra­di­a­tion, with longer wave­lengths. For ex­am­ple, the Sun is ap­prox­i­mately 6,000 K (5,730 °C; 10,340 °F), its ra­di­a­tion peaks near 500 nm, and is vis­i­ble to the human eye. Earth is ap­prox­i­mately 290 K (17 °C; 62 °F), so its ra­di­a­tion peaks near 10,000 nm, and is much too long to be vis­i­ble to hu­mans.

Be­cause of its tem­per­a­ture, the at­mos­phere emits in­frared ra­di­a­tion. For ex­am­ple, on clear nights Earth’s sur­face cools down faster than on cloudy nights. This is be­cause clouds (H2O) are strong ab­sorbers and emit­ters of in­frared ra­di­a­tion. This is also why it be­comes colder at night at higher el­e­va­tions.

The green­house ef­fect is di­rectly re­lated to this ab­sorp­tion and emis­sion ef­fect. Some gases in the at­mos­phere ab­sorb and emit in­frared ra­di­a­tion, but do not in­ter­act with sun­light in the vis­i­ble spec­trum. Com­mon ex­am­ples of these are CO
2 and H2O.

Refractive index

Distortive effect of atmospheric refraction upon the shape of the sun at the horizon.

Distortive effect of atmospheric refraction upon the shape of the sun at the horizon.Main article: Atmospheric refractionSee also: Scintillation (astronomy)

The re­frac­tive index of air is close to, but just greater than 1. Sys­tem­atic vari­a­tions in re­frac­tive index can lead to the bend­ing of light rays over long op­ti­cal paths. One ex­am­ple is that, under some cir­cum­stances, ob­servers on­board ships can see other ves­sels just over the hori­zon be­cause light is re­fracted in the same di­rec­tion as the cur­va­ture of Earth’s sur­face.

The re­frac­tive index of air de­pends on temperature,[40] giv­ing rise to re­frac­tion ef­fects when the tem­per­a­ture gra­di­ent is large. An ex­am­ple of such ef­fects is the mi­rage.


Main article: Atmospheric circulation

An idealised view of three pairs of large circulation cells.

An idealised view of three pairs of large circulation cells.

At­mos­pheric circulation is the large-scale move­ment of air through the tro­pos­phere, and the means (with ocean cir­cu­la­tion) by which heat is dis­trib­uted around Earth. The large-scale struc­ture of the at­mos­pheric cir­cu­la­tion varies from year to year, but the basic struc­ture re­mains fairly con­stant be­cause it is de­ter­mined by Earth’s ro­ta­tion rate and the dif­fer­ence in solar ra­di­a­tion be­tween the equa­tor and poles.

Evolution of Earth’s atmosphere

See also: History of Earth and Paleoclimatology

Earliest atmosphere

The first at­mos­phere con­sisted of gases in the solar neb­ula, pri­mar­ily hy­dro­gen. There were prob­a­bly sim­ple hy­drides such as those now found in the gas gi­ants (Jupiter and Sat­urn), no­tably water vapor, methane and am­mo­nia.[41]

Second atmosphere

Out­gassing from vol­can­ism, sup­ple­mented by gases pro­duced dur­ing the late heavy bom­bard­ment of Earth by huge as­ter­oids, pro­duced the next at­mos­phere, con­sist­ing largely of ni­tro­gen plus car­bon diox­ide and inert gases.[41] A major part of car­bon-diox­ide emis­sions dis­solved in water and re­acted with met­als such as cal­cium and mag­ne­sium dur­ing weath­er­ing of crustal rocks to form car­bon­ates that were de­posited as sed­i­ments. Wa­ter-re­lated sed­i­ments have been found that date from as early as 3.8 bil­lion years ago.[42]

About 3.4 bil­lion years ago, ni­tro­gen formed the major part of the then sta­ble “sec­ond at­mos­phere”. The in­flu­ence of life has to be taken into ac­count rather soon in the his­tory of the at­mos­phere, be­cause hints of early life-forms ap­pear as early as 3.5 bil­lion years ago.[43] How Earth at that time main­tained a cli­mate warm enough for liq­uid water and life, if the early Sun put out 30% lower solar ra­di­ance than today, is a puz­zle known as the “faint young Sun para­dox“.

The ge­o­log­i­cal record how­ever shows a con­tin­u­ous rel­a­tively warm sur­face dur­ing the com­plete early tem­per­a­ture record of Earth – with the ex­cep­tion of one cold glacial phase about 2.4 bil­lion years ago. In the late Archean Eon an oxy­gen-con­tain­ing at­mos­phere began to de­velop, ap­par­ently pro­duced by pho­to­syn­the­siz­ing cyanobac­te­ria (see Great Oxy­gena­tion Event), which have been found as stro­ma­to­lite fos­sils from 2.7 bil­lion years ago. The early basic car­bon iso­topy (iso­tope ratio pro­por­tions) strongly sug­gests con­di­tions sim­i­lar to the cur­rent, and that the fun­da­men­tal fea­tures of the car­bon cycle be­came es­tab­lished as early as 4 bil­lion years ago.

An­cient sed­i­ments in the Gabon dat­ing from be­tween about 2.15 and 2.08 bil­lion years ago pro­vide a record of Earth’s dy­namic oxy­gena­tion evo­lu­tion. These fluc­tu­a­tions in oxy­gena­tion were likely dri­ven by the Lo­ma­gundi car­bon iso­tope excursion.[44]

Third atmosphere

Oxygen content of the atmosphere over the last billion years[45][46]

Oxygen content of the atmosphere over the last billion years[45][46]

The con­stant re-arrange­ment of con­ti­nents by plate tec­ton­ics in­flu­ences the long-term evo­lu­tion of the at­mos­phere by trans­fer­ring car­bon diox­ide to and from large con­ti­nen­tal car­bon­ate stores. Free oxy­gen did not exist in the at­mos­phere until about 2.4 bil­lion years ago dur­ing the Great Oxy­gena­tion Event and its ap­pear­ance is in­di­cated by the end of the banded iron for­ma­tions.

Be­fore this time, any oxy­gen pro­duced by pho­to­syn­the­sis was con­sumed by ox­i­da­tion of re­duced ma­te­ri­als, no­tably iron. Mol­e­cules of free oxy­gen did not start to ac­cu­mu­late in the at­mos­phere until the rate of pro­duc­tion of oxy­gen began to ex­ceed the avail­abil­ity of re­duc­ing ma­te­ri­als that re­moved oxy­gen. This point sig­ni­fies a shift from a re­duc­ing at­mos­phere to an ox­i­diz­ing at­mos­phere. O2 showed major vari­a­tions until reach­ing a steady state of more than 15% by the end of the Precambrian.[47] The fol­low­ing time span from 541 mil­lion years ago to the pre­sent day is the Phanero­zoic Eon, dur­ing the ear­li­est pe­riod of which, the Cam­brian, oxy­gen-re­quir­ing meta­zoan life forms began to ap­pear.

The amount of oxy­gen in the at­mos­phere has fluc­tu­ated over the last 600 mil­lion years, reach­ing a peak of about 30% around 280 mil­lion years ago, sig­nif­i­cantly higher than today’s 21%. Two main processes gov­ern changes in the at­mos­phere: Plants using car­bon diox­ide from the at­mos­phere and re­leas­ing oxy­gen, and then plants using some oxy­gen at night by the process of pho­tores­pi­ra­tion with the re­main­der of the oxy­gen being used to break­down ad­ja­cent or­ganic ma­te­r­ial. Break­down of pyrite and vol­canic erup­tions re­lease sul­fur into the at­mos­phere, which ox­i­dizes and hence re­duces the amount of oxy­gen in the at­mos­phere. How­ever, vol­canic erup­tions also re­lease car­bon diox­ide, which plants can con­vert to oxy­gen. The exact cause of the vari­a­tion of the amount of oxy­gen in the at­mos­phere is not known. Pe­ri­ods with much oxy­gen in the at­mos­phere are as­so­ci­ated with rapid de­vel­op­ment of an­i­mals. Today’s at­mos­phere con­tains 21% oxy­gen, which is great enough for this rapid de­vel­op­ment of animals.[48]

Air pollution

Main article: Air pollution

Air pollution is the in­tro­duc­tion into the at­mos­phere of chem­i­calspar­tic­u­late mat­ter or bi­o­log­i­cal ma­te­ri­als that cause harm or dis­com­fort to organisms.[49] Stratos­pheric ozone de­ple­tion is caused by air pol­lu­tion, chiefly from chlo­ro­flu­o­ro­car­bons and other ozone-de­plet­ing sub­stances.

The sci­en­tific con­sen­sus is that the an­thro­pogenic green­house gases cur­rently ac­cu­mu­lat­ing in the at­mos­phere are the main cause of global warm­ing.[50]File:Watching the Earth Breathe.ogvPlay mediaAnimation shows the buildup of tropospheric CO
2 in the Northern Hemisphere with a maximum around May. The maximum in the vegetation cycle follows in the late summer. Following the peak in vegetation, the drawdown of atmospheric CO
2 due to photosynthesis is apparent, particularly over the boreal forests.

Images from space

Main article: Weather satellite

On Oc­to­ber 19, 2015, NASA started a web­site con­tain­ing daily im­ages of the full sun­lit side of Earth on http://​epic.​gsfc.​nasa.​gov/​. The im­ages are taken from the Deep Space Cli­mate Ob­ser­va­tory (DSCOVR) and show Earth as it ro­tates dur­ing a day.[51]

  • Blue light is scat­tered more than other wave­lengths by the gases in the at­mos­phere, giv­ing Earth a blue halo when seen from space.
  • The ge­o­mag­netic storms cause dis­plays of au­rora across the at­mos­phere.
  • Limb view, of Earth’s at­mos­phere. Col­ors roughly de­note the lay­ers of the at­mos­phere.
  • This image shows the Moon at the cen­tre, with the limb of Earth near the bot­tom tran­si­tion­ing into the or­ange-col­ored tro­pos­phere. The tro­pos­phere ends abruptly at the tropopause, which ap­pears in the image as the sharp bound­ary be­tween the or­ange- and blue-col­ored at­mos­phere. The sil­very-blue noc­tilu­cent clouds ex­tend far above Earth’s tro­pos­phere.
  • Earth’s at­mos­phere back­lit by the Sun in an eclipse ob­served from deep space on­board Apollo 12 in 1969.



From Wikipedia, the free encyclopedia

This article is about the atmospheric process. For the geological process, see Weathering. For other uses, see Weather (disambiguation) and Weather systems (disambiguation).

Thunderstorm near Garajau, Madeira

Thunderstorm near Garajau, Madeira

Part of a series on
Temperate and polar seasonsWinter Spring Summer Autumn
Tropical seasonsDry season Harmattan Wet season
StormsCloud Cumulonimbus cloud Arcus cloud Downburst Microburst Heat burst Derecho Lightning Volcanic lightning Thunderstorm Air-mass thunderstorm Thundersnow Dry thunderstorm Mesocyclone Supercell Tornado Anticyclonic tornado Landspout Waterspout Dust devil Fire whirl Anticyclone Cyclone Polar low Extratropical cyclone European windstorm Nor’easter Subtropical cyclone Tropical cyclone Atlantic hurricane Typhoon Storm surge Dust storm Simoom Haboob Monsoon Amihan Gale Sirocco Firestorm Winter storm Ice storm Blizzard Ground blizzard Snowsquall
PrecipitationDrizzle Freezing Graupel Hail Megacryometeor Ice pellets Diamond dust Rain Freezing Cloudburst Snow Rain and snow mixed Snow grains Snow roller Slush
TopicsAir pollution AtmosphereChemistry Convection Physics River
GlossariesMeteorology Climate change Tornado terms Tropical cyclone terms
 Weather portal

Weather is the state of the at­mos­phere, de­scrib­ing for ex­am­ple the de­gree to which it is hot or cold, wet or dry, calm or stormy, clear or cloudy. Most weather phe­nom­ena occur in the low­est level of the at­mos­phere, the tro­pos­phere, just below the stratos­phere. Weather refers to day-to-day tem­per­a­ture and pre­cip­i­ta­tion ac­tiv­ity, whereas cli­mate is the term for the av­er­ag­ing of at­mos­pheric con­di­tions over longer pe­ri­ods of time. When used with­out qual­i­fi­ca­tion, “weather” is gen­er­ally un­der­stood to mean the weather of Earth.

Weather is dri­ven by air pres­sure, tem­per­a­ture and mois­ture dif­fer­ences be­tween one place and an­other. These dif­fer­ences can occur due to the sun’s angle at any par­tic­u­lar spot, which varies with lat­i­tude. The strong tem­per­a­ture con­trast be­tween polar and trop­i­cal air gives rise to the largest scale at­mos­pheric cir­cu­la­tions: the Hadley Cell, the Fer­rel Cell, the Polar Cell, and the jet stream. Weather sys­tems in the mid-lat­i­tudes, such as ex­tra­t­rop­i­cal cy­clones, are caused by in­sta­bil­i­ties of the jet stream­flow. Be­cause the Earth’s axis is tilted rel­a­tive to its or­bital plane, sun­light is in­ci­dent at dif­fer­ent an­gles at dif­fer­ent times of the year. On Earth’s sur­face, tem­per­a­tures usu­ally range ±40 °C (−40 °F to 100 °F) an­nu­ally. Over thou­sands of years, changes in Earth’s orbit can af­fect the amount and dis­tri­b­u­tion of solar en­ergy re­ceived by the Earth, thus in­flu­enc­ing long-term cli­mate and global cli­mate change.

Sur­face tem­per­a­ture dif­fer­ences in turn cause pres­sure dif­fer­ences. Higher al­ti­tudes are cooler than lower al­ti­tudes, as most at­mos­pheric heat­ing is due to con­tact with the Earth’s sur­face while ra­dia­tive losses to space are mostly con­stant. Weather fore­cast­ing is the ap­pli­ca­tion of sci­ence and tech­nol­ogy to pre­dict the state of the at­mos­phere for a fu­ture time and a given lo­ca­tion. The Earth’s weather sys­tem is a chaotic sys­tem; as a re­sult, small changes to one part of the sys­tem can grow to have large ef­fects on the sys­tem as a whole. Human at­tempts to con­trol the weather have oc­curred through­out his­tory, and there is ev­i­dence that human ac­tiv­i­ties such as agri­cul­ture and in­dus­try have mod­i­fied weather pat­terns.

Study­ing how the weather works on other plan­ets has been help­ful in un­der­stand­ing how weather works on Earth. A fa­mous land­mark in the Solar Sys­temJupiter‘s Great Red Spot, is an an­ti­cy­clonic storm known to have ex­isted for at least 300 years. How­ever, the weather is not lim­ited to plan­e­tary bod­ies. A star’s corona is con­stantly being lost to space, cre­at­ing what is es­sen­tially a very thin at­mos­phere through­out the Solar Sys­tem. The move­ment of mass ejected from the Sun is known as the solar wind.



Cumulus mediocris cloud surrounded by stratocumulus

Cumulus mediocris cloud surrounded by stratocumulus

On Earth, the com­mon weather phe­nom­ena in­clude wind, cloud, rain, snow, fog and dust storms. Less com­mon events in­clude nat­ural dis­as­ters such as tor­na­doeshur­ri­canesty­phoons and ice storms. Al­most all fa­mil­iar weather phe­nom­ena occur in the tro­pos­phere (the lower part of the atmosphere). Weather does occur in the stratos­phere and can af­fect weather lower down in the tro­pos­phere, but the exact mech­a­nisms are poorly understood.

Weather oc­curs pri­mar­ily due to air pres­sure, tem­per­a­ture and mois­ture dif­fer­ences be­tween one place to an­other. These dif­fer­ences can occur due to the sun angle at any par­tic­u­lar spot, which varies by lat­i­tude from the trop­ics. In other words, the far­ther from the trop­ics one lies, the lower the sun angle is, which causes those lo­ca­tions to be cooler due to the spread of the sun­light over a greater surface. The strong tem­per­a­ture con­trast be­tween polar and trop­i­cal air gives rise to the large scale at­mos­pheric cir­cu­la­tion cells and the jet stream. Weather sys­tems in the mid-lat­i­tudes, such as ex­tra­t­rop­i­cal cy­clones, are caused by in­sta­bil­i­ties of the jet stream flow (see baro­clin­ity). Weather sys­tems in the trop­ics, such as mon­soons or or­ga­nized thun­der­storm sys­tems, are caused by dif­fer­ent processes.

2015 – Warmest Global Year on Record (since 1880) – Colors indicate temperature anomalies (NASA/NOAA; 20 January 2016).[9]

2015 – Warmest Global Year on Record (since 1880) – Colors indicate temperature anomalies (NASA/NOAA; 20 January 2016).

Be­cause the Earth’s axis is tilted rel­a­tive to its or­bital plane, sun­light is in­ci­dent at dif­fer­ent an­gles at dif­fer­ent times of the year. In June the North­ern Hemi­sphere is tilted to­wards the sun, so at any given North­ern Hemi­sphere lat­i­tude sun­light falls more di­rectly on that spot than in De­cem­ber (see Ef­fect of sun angle on cli­mate). This ef­fect causes sea­sons. Over thou­sands to hun­dreds of thou­sands of years, changes in Earth’s or­bital pa­ra­me­ters af­fect the amount and dis­tri­b­u­tion of solar en­ergy re­ceived by the Earth and in­flu­ence long-term cli­mate. (See Mi­lankovitch cy­cles).

The un­even solar heat­ing (the for­ma­tion of zones of tem­per­a­ture and mois­ture gra­di­ents, or fron­to­ge­n­e­sis) can also be due to the weather it­self in the form of cloudi­ness and precipitation. Higher al­ti­tudes are typ­i­cally cooler than lower al­ti­tudes, which the re­sult of higher sur­face tem­per­a­ture and ra­di­a­tional heat­ing, which pro­duces the adi­a­batic lapse rate. In some sit­u­a­tions, the tem­per­a­ture ac­tu­ally in­creases with height. This phe­nom­e­non is known as an in­ver­sion and can cause moun­tain­tops to be warmer than the val­leys below. In­ver­sions can lead to the for­ma­tion of fog and often act as a cap that sup­presses thun­der­storm de­vel­op­ment. On local scales, tem­per­a­ture dif­fer­ences can occur be­cause dif­fer­ent sur­faces (such as oceans, forests, ice sheets, or man-made ob­jects) have dif­fer­ing phys­i­cal char­ac­ter­is­tics such as re­flec­tiv­ity, rough­ness, or mois­ture con­tent.

Sur­face tem­per­a­ture dif­fer­ences in turn cause pres­sure dif­fer­ences. A hot sur­face warms the air above it caus­ing it to ex­pand and lower the den­sity and the re­sult­ing sur­face air pres­sure. The re­sult­ing hor­i­zon­tal pres­sure gra­di­ent moves the air from higher to lower pres­sure re­gions, cre­at­ing a wind, and the Earth’s ro­ta­tion then causes de­flec­tion of this air­flow due to the Cori­o­lis ef­fect. The sim­ple sys­tems thus formed can then dis­play emer­gent be­hav­iour to pro­duce more com­plex sys­tems and thus other weather phe­nom­ena. Large scale ex­am­ples in­clude the Hadley cell while a smaller scale ex­am­ple would be coastal breezes.

The at­mos­phere is a chaotic sys­tem. As a re­sult, small changes to one part of the sys­tem can ac­cu­mu­late and mag­nify to cause large ef­fects on the sys­tem as a whole. This at­mos­pheric in­sta­bil­ity makes weather fore­cast­ing less pre­dictable than tides or eclipses.[18] Al­though it is dif­fi­cult to ac­cu­rately pre­dict weather more than a few days in ad­vance, weather fore­cast­ers are con­tin­u­ally work­ing to ex­tend this limit through me­te­o­ro­log­i­cal re­search and re­fin­ing cur­rent method­olo­gies in weather pre­dic­tion. How­ever, it is the­o­ret­i­cally im­pos­si­ble to make use­ful day-to-day pre­dic­tions more than about two weeks ahead, im­pos­ing an upper limit to po­ten­tial for im­proved pre­dic­tion skill.

Shaping the planet Earth

Main article: Weathering

Weather is one of the fun­da­men­tal processes that shape the Earth. The process of weath­er­ing breaks down the rocks and soils into smaller frag­ments and then into their con­stituent substances. Dur­ing rains pre­cip­i­ta­tion, the water droplets ab­sorb and dis­solve car­bon diox­ide from the sur­round­ing air. This causes the rain­wa­ter to be slightly acidic, which aids the ero­sive prop­er­ties of water. The re­leased sed­i­ment and chem­i­cals are then free to take part in chem­i­cal re­ac­tions that can af­fect the sur­face fur­ther (such as acid rain), and sodium and chlo­ride ions (salt) de­posited in the seas/oceans. The sed­i­ment may re­form in time and by ge­o­log­i­cal forces into other rocks and soils. In this way, weather plays a major role in ero­sion of the surface.

Effect on humans

Further information: Biometeorology

Weather, seen from an an­thro­po­log­i­cal per­spec­tive, is some­thing all hu­mans in the world con­stantly ex­pe­ri­ence through their senses, at least while being out­side. There are so­cially and sci­en­tif­i­cally con­structed un­der­stand­ings of what weather is, what makes it change, the ef­fect it has on hu­mans in dif­fer­ent sit­u­a­tions, etc. There­fore, weather is some­thing peo­ple often com­mu­ni­cate about.

Effects on populations

New Orleans, Louisiana, after being struck by Hurricane Katrina. Katrina was a Category 3 hurricane when it struck although it had been a category 5 hurricane in the Gulf of Mexico.

New Orleans, Louisiana, after being struck by Hurricane Katrina. Katrina was a Category 3 hurricane when it struck although it had been a category 5 hurricane in the Gulf of Mexico.

The weather has played a large and some­times di­rect part in human his­tory. Aside from cli­matic changes that have caused the grad­ual drift of pop­u­la­tions (for ex­am­ple the de­ser­ti­fi­ca­tion of the Mid­dle East, and the for­ma­tion of land bridges dur­ing glacial pe­ri­ods), ex­treme weather events have caused smaller scale pop­u­la­tion move­ments and in­truded di­rectly in his­tor­i­cal events. One such event is the sav­ing of Japan from in­va­sion by the Mon­gol fleet of Kublai Khan by the Kamikaze winds in 1281. French claims to Florida came to an end in 1565 when a hur­ri­cane de­stroyed the French fleet, al­low­ing Spain to con­quer Fort Car­o­line. More re­cently, Hur­ri­cane Ka­t­rina re­dis­trib­uted over one mil­lion peo­ple from the cen­tral Gulf coast else­where across the United States, be­com­ing the largest di­as­pora in the his­tory of the United States.

The Lit­tle Ice Age caused crop fail­ures and famines in Eu­rope. The 1690s saw the worst famine in France since the Mid­dle Ages. Fin­land suf­fered a se­vere famine in 1696–1697, dur­ing which about one-third of the Finnish pop­u­la­tion died.


Main article: Weather forecasting

Forecast of surface pressures five days into the future for the north Pacific, North America, and the north Atlantic Ocean as on 9 June 2008

Forecast of surface pressures five days into the future for the north Pacific, North America, and the north Atlantic Ocean as on 9 June 2008

Weather fore­cast­ing is the ap­pli­ca­tion of sci­ence and tech­nol­ogy to pre­dict the state of the at­mos­phere for a fu­ture time and a given lo­ca­tion. Human be­ings have at­tempted to pre­dict the weather in­for­mally for mil­len­nia, and for­mally since at least the nine­teenth century. Weather fore­casts are made by col­lect­ing quan­ti­ta­tive data about the cur­rent state of the at­mos­phere and using sci­en­tific un­der­stand­ing of at­mos­pheric processes to pro­ject how the at­mos­phere will evolve.

Once an all-hu­man en­deavor based mainly upon changes in baro­met­ric pres­sure, cur­rent weather con­di­tions, and sky condition, fore­cast mod­els are now used to de­ter­mine fu­ture con­di­tions. On the other hand, human input is still re­quired to pick the best pos­si­ble fore­cast model to base the fore­cast upon, which in­volve many dis­ci­plines such as pat­tern recog­ni­tion skills, tele­con­nec­tions, knowl­edge of model per­for­mance, and knowl­edge of model bi­ases.

The chaotic na­ture of the at­mos­phere, the mas­sive com­pu­ta­tional power re­quired to solve the equa­tions that de­scribe the at­mos­phere, the error in­volved in mea­sur­ing the ini­tial con­di­tions, and an in­com­plete un­der­stand­ing of at­mos­pheric processes mean that fore­casts be­come less ac­cu­rate as of the dif­fer­ence in cur­rent time and the time for which the fore­cast is being made (the range of the fore­cast) in­creases. The use of en­sem­bles and model con­sen­sus helps to nar­row the error and pick the most likely outcome.

There are a va­ri­ety of end users to weather fore­casts. Weather warn­ings are im­por­tant fore­casts be­cause they are used to pro­tect life and property. Fore­casts based on tem­per­a­ture and pre­cip­i­ta­tion are im­por­tant to agriculture, and there­fore to com­mod­ity traders within stock mar­kets. Tem­per­a­ture fore­casts are used by util­ity com­pa­nies to es­ti­mate de­mand over com­ing days.

In some areas, peo­ple use weather fore­casts to de­ter­mine what to wear on a given day. Since out­door ac­tiv­i­ties are se­verely cur­tailed by heavy rainsnow and the wind chill, fore­casts can be used to plan ac­tiv­i­ties around these events and to plan ahead to sur­vive through them.

Trop­i­cal weather fore­cast­ing is dif­fer­ent from that at higher lat­i­tudes. The sun shines more di­rectly on the trop­ics than on higher lat­i­tudes (at least in the av­er­age over a year), which makes the trop­ics warm (Stevens 2011). And, the ver­ti­cal di­rec­tion (up, as one stands on the Earth’s sur­face) is per­pen­dic­u­lar to the Earth’s axis of ro­ta­tion at the equa­tor, while the axis of ro­ta­tion and the ver­ti­cal are the same at the pole; this causes the Earth’s ro­ta­tion to in­flu­ence the at­mos­pheric cir­cu­la­tion more strongly at high lat­i­tudes than low. Be­cause of these two fac­tors, clouds and rain­storms in the trop­ics can occur more spon­ta­neously com­pared to those at higher lat­i­tudes, where they are more tightly con­trolled by larger-scale forces in the at­mos­phere. Be­cause of these dif­fer­ences, clouds and rain are more dif­fi­cult to fore­cast in the trop­ics than at higher lat­i­tudes. On the other hand, the tem­per­a­ture is eas­ily fore­cast in the trop­ics, be­cause it doesn’t change much.


The as­pi­ra­tion to con­trol the weather is ev­i­dent through­out human his­tory: from an­cient rit­u­als in­tended to bring rain for crops to the U.S. Mil­i­tary Op­er­a­tion Pop­eye, an at­tempt to dis­rupt sup­ply lines by length­en­ing the North Viet­namese mon­soon. The most suc­cess­ful at­tempts at in­flu­enc­ing weather in­volve cloud seed­ing; they in­clude the fog– and low stra­tus dis­per­sion tech­niques em­ployed by major air­ports, tech­niques used to in­crease win­ter pre­cip­i­ta­tion over moun­tains, and tech­niques to sup­press hail. A re­cent ex­am­ple of weather con­trol was China’s prepa­ra­tion for the 2008 Sum­mer Olympic Games. China shot 1,104 rain dis­per­sal rock­ets from 21 sites in the city of Bei­jing in an ef­fort to keep rain away from the open­ing cer­e­mony of the games on 8 Au­gust 2008. Guo Hu, head of the Bei­jing Mu­nic­i­pal Me­te­o­ro­log­i­cal Bu­reau (BMB), con­firmed the suc­cess of the op­er­a­tion with 100 mil­lime­ters falling in Baod­ing City of Hebei Province, to the south­west and Bei­jing’s Fang­shan Dis­trict record­ing a rain­fall of 25 millimeters.

Whereas there is in­con­clu­sive ev­i­dence for these tech­niques’ ef­fi­cacy, there is ex­ten­sive ev­i­dence that human ac­tiv­ity such as agri­cul­ture and in­dus­try re­sults in in­ad­ver­tent weather modification:

The ef­fects of in­ad­ver­tent weather mod­i­fi­ca­tion may pose se­ri­ous threats to many as­pects of civ­i­liza­tion, in­clud­ing ecosys­temsnat­ural re­sources, food and fiber pro­duc­tion, eco­nomic de­vel­op­ment, and human health.

Microscale meteorology

Mi­croscale me­te­o­rol­ogy is the study of short-lived at­mos­pheric phe­nom­ena smaller than mesoscale, about 1 km or less. These two branches of me­te­o­rol­ogy are some­times grouped to­gether as “mesoscale and mi­croscale me­te­o­rol­ogy” (MMM) and to­gether study all phe­nom­ena smaller than syn­op­tic scale; that is they study fea­tures gen­er­ally too small to be de­picted on a weather map. These in­clude small and gen­er­ally fleet­ing cloud “puffs” and other small cloud features.

Extremes on Earth

Early morning sunshine over Bratislava, Slovakia. February 2008.

Early morning sunshine over Bratislava, Slovakia. February 2008.

The same area, just three hours later, after light snowfall

The same area, just three hours later, after light snowfallMain articles: Extremes on Earth and List of weather records

On Earth, tem­per­a­tures usu­ally range ±40 °C (100 °F to −40 °F) an­nu­ally. The range of cli­mates and lat­i­tudes across the planet can offer ex­tremes of tem­per­a­ture out­side this range. The cold­est air tem­per­a­ture ever recorded on Earth is −89.2 °C (−128.6 °F), at Vos­tok Sta­tionAntarc­tica on 21 July 1983. The hottest air tem­per­a­ture ever recorded was 57.7 °C (135.9 °F) at ‘Az­iziya, Libya, on 13 Sep­tem­ber 1922, but that read­ing is queried. The high­est recorded av­er­age an­nual tem­per­a­ture was 34.4 °C (93.9 °F) at Dal­lol, Ethiopia. The cold­est recorded av­er­age an­nual tem­per­a­ture was −55.1 °C (−67.2 °F) at Vos­tok Sta­tionAntarc­tica.

The cold­est av­er­age an­nual tem­per­a­ture in a per­ma­nently in­hab­ited lo­ca­tion is at Eu­reka, Nunavut, in Canada, where the an­nual av­er­age tem­per­a­ture is −19.7 °C (−3.5 °F).

Extraterrestrial within the Solar System

Jupiter's Great Red Spot in February 1979, photographed by the unmanned Voyager 1 NASA space probe.

Jupiter’s Great Red Spot in February 1979, photographed by the unmanned Voyager 1 NASA space probe.

Study­ing how the weather works on other plan­ets has been seen as help­ful in un­der­stand­ing how it works on Earth. Weather on other plan­ets fol­lows many of the same phys­i­cal prin­ci­ples as weather on Earth, but oc­curs on dif­fer­ent scales and in at­mos­pheres hav­ing dif­fer­ent chem­i­cal com­po­si­tion. The Cassini–Huy­gens mis­sion to Titan dis­cov­ered clouds formed from methane or ethane which de­posit rain com­posed of liq­uid methane and other or­ganic com­pounds. Earth’s at­mos­phere in­cludes six lat­i­tu­di­nal cir­cu­la­tion zones, three in each hemisphere. In con­trast, Jupiter’s banded ap­pear­ance shows many such zones, Titan has a sin­gle jet stream near the 50th par­al­lel north latitude, and Venus has a sin­gle jet near the equator.

One of the most fa­mous land­marks in the Solar Sys­temJupiter‘s Great Red Spot, is an an­ti­cy­clonic storm known to have ex­isted for at least 300 years. On other gas gi­ants, the lack of a sur­face al­lows the wind to reach enor­mous speeds: gusts of up to 600 me­tres per sec­ond (about 2,100 km/h or 1,300 mph) have been mea­sured on the planet Nep­tune. This has cre­ated a puz­zle for plan­e­tary sci­en­tists. The weather is ul­ti­mately cre­ated by solar en­ergy and the amount of en­ergy re­ceived by Nep­tune is only about 1900 of that re­ceived by Earth, yet the in­ten­sity of weather phe­nom­ena on Nep­tune is far greater than on Earth. The strongest plan­e­tary winds dis­cov­ered so far are on the ex­tra­so­lar planet HD 189733 b, which is thought to have east­erly winds mov­ing at more than 9,600 kilo­me­tres per hour (6,000 mph).

Space weather

Aurora Borealis

Aurora BorealisMain article: Space weather

Weather is not lim­ited to plan­e­tary bod­ies. Like all stars, the Sun’s corona is con­stantly being lost to space, cre­at­ing what is es­sen­tially a very thin at­mos­phere through­out the Solar Sys­tem. The move­ment of mass ejected from the Sun is known as the solar wind. In­con­sis­ten­cies in this wind and larger events on the sur­face of the star, such as coro­nal mass ejec­tions, form a sys­tem that has fea­tures anal­o­gous to con­ven­tional weather sys­tems (such as pres­sure and wind) and is gen­er­ally known as space weather. Coro­nal mass ejec­tions have been tracked as far out in the Solar Sys­tem as Sat­urn. The ac­tiv­ity of this sys­tem can af­fect plan­e­tary at­mos­pheres and oc­ca­sion­ally sur­faces. The in­ter­ac­tion of the solar wind with the ter­res­trial at­mos­phere can pro­duce spec­tac­u­lar au­ro­rae, and can play havoc with elec­tri­cally sen­si­tive sys­tems such as elec­tric­ity grids and radio signals


Are We Made of Star Stuff? | Life Behind the Stars | Spark
After many years with Carl Sagan’s haunting phrase echoing in his head, a scientist decides to find a link between the stars that make up our universe and life on Earth. A journey through some of the best research centres in the world looking for that amazing link between life and the rest of the Universe.
Cosmic Journeys – Hubble: Universe in Motion SpaceRip
Since its launch 25 Years ago, the Hubble Telescope has returned images of unprecedented beauty of a dynamic and changing universe. In this episode of COSMIC JOURNEYS, Hubble’s most iconic images are bought to life to answer some of the most important questions facing astronomers today. Colliding galaxies, the birth and death of stars, jets of gas thrown out by material crashing into distant suns: these incredible images tech us valuable lessons about how galaxies are formed, what dark matter is and even the fate of the earth itself. ABOUT US Here at SpaceRip, we value the exploration of the unknown. We surpass boundaries for the sake of uncovering the mysteries of the cosmos and what they may tell us about our origin and our future. With our videos, we hope to educate our viewers on how we fit into the universe, and more so how we can do our part to better it. We believe there is no better time to inform ourselves about the world around us. Our partnership with MagellanTV is aimed to educate viewers on our complex world to prepare for our rapidly changing future. Through our videos we hope to capture a variety of important topics with the overall goal of promoting positive discussion and action.