Earth's Atmosphere: Composition, Climate & Weather
The division of the atmosphere into layers mostly by on temperature and not on the gas pressure or density. Computer Drawing of the equations used to model the Earth's atmosphere in both the temperature and the pressure through the equation of state and also The model assumes that the pressure and temperature change only with altitude. Earth's Atmosphere can be divided into four layers with distinct changes in temperature as the altitude increases. Starti ng at Earth's surface.
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 Mayglints 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. 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 scatteringshorter 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.
Earth's Atmosphere: Composition, Climate & Weather
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. 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 nanometers. 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 opacityallowing the transmission of only certain bands of light. 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. 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.
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.
Temperature Changes With Earth’s Atmosphere
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 CO2 and H2O. Refractive index See 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,  giving rise to refraction effects when the temperature gradient is large.
An example of such effects is the mirage. Atmospheric circulation An idealised view of three large circulation cells.
Atmospheric Temperature and Pressure - Our Atmosphere - Geography for Kids
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 nebulaprimarily hydrogen.
There were probably simple hydrides such as those now found in the gas giants Jupiter and Saturnnotably water vapor, methane and ammonia. Water-related sediments have been found that date from as early as 3. 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. 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.
In the late Archean Eon an oxygen-containing atmosphere began to develop, apparently produced by photosynthesizing cyanobacteria see Great Oxygenation Eventwhich have been found as stromatolite fossils from 2. 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, and 2, million years ago provide a record of Earth's dynamic oxygenation evolution. These fluctuations in oxygenation were likely driven by the Lomagundi carbon isotope excursion.
Structure of the Atmosphere | North Carolina Climate Office
Free oxygen did not exist in the atmosphere until about 2. 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. The effect of latitude, tropical climate, constant gentle wind and sea-side locations show smaller average temperature ranges, smaller variations of temperature, and a higher average temperature second graph, taken for the same period as Campinas, at Aracajucapital of the state of Sergipealso in Brazil, at a latitude of 10 degrees, nearer to the Equator.
Average maximum yearly temperature is The average temperature range is 5. Temperature variation along the year in Aracaju is very damped standard deviation of 1.
Most of the places with these characteristics are located in the transition between temperate and tropical climates, approximately around the tropicsparticularly in the Southern hemisphere the tropic of Capricorn. Surface temperature inversion The minimum temperature on calm, clear nights has been observed to occur not on the ground, but rather a few tens of centimeters above the ground.
The lowest temperature layer is called Ramdas layer after L. Finally, as you continue to travel outward leaving the atmosphere via the exosphere, the temperature drops again, becoming very cold. Have you ever stood by a camp fire?
The closer you get to the fire, what happens? As you hold your hands in front of you near the flames, do you feel the heat? What happens as you pull away from the fire? The further you draw away from the fire, the less heat your body feels.
Each time the atmosphere warms up, there must be something that is warming it. The closer you get to the thing warming it up, the more you can feel the heat. The further away you get from that heat source, the cooler the air becomes.