The atmosphere of the is composed of different kinds of layer. it consists of 5 kinds of layer. It is thickest near the surface and thins out with height until it eventually merges with space. The types of ozone are as follows:
it is the first atmospheric layer of the earth which contains around 80% of the mass of the total atmosphere. Although the heights of each layer can vary due to changing weather and climate conditions, the Troposphere extends up to 20 km above sea level. The content of water vapor and temperature rapidly decreases with altitude in the troposphere.The troposphere contains 99 % of the water vapor in the atmosphere whose concentration vary with latitude which absorbs solar energy and thermal radiation from the planet's surface and plays a major role in regulating air temperature. They are greatest above the tropics, where they may be as high as 3 %, and decrease toward the polar regions. The fraction of the gases which makes up the atmosphere are found in the troposphere as being a lower layer and as a result of pull of gravity.All weather phenomena occur within the troposphere, although turbulence may extend into the lower portion of the stratosphere. Troposphere means "region of mixing" and is so named because of vigorous convective air currents within the layer.The upper boundary of the layer is known as the
tropopause,which ranges in height from 5 miles (8 km) near the poles up to 11 miles (18 km) above the equator. Its height also varies with the seasons; highest in the summer and lowest in the winter.
The Latin word, 'stratus' meaning 'spreading out' has given birth to the word, 'stratosphere. The stratosphere is the second major strata of air in the atmosphere which extends above the tropopause to an altitude of about 30 miles (50 km) above the planet's surface. It consists of ozone layer which is located between 15 to 35 km above the surface of the Earth. The ozone layer consists of large amount of ozone gas. it absorbs the sun ultraviolet radiation coming directly to the earth surface and saves from harmful effect. Ozone plays the major role in regulating the thermal regime of the stratosphere, as water vapor content within the layer is very low.The air temperature remains relatively constant up to an altitude of 15 miles (25 km)and then increases gradually to up to the
stratopause. As air temperature in the stratosphere increases with altitude, it does not cause convection and has a stabilizing effect on atmospheric conditions in the region. Temperature increases with ozone concentration. Absorption of ultraviolet radiation by ozone molecules converts solar energy into kinetic energy , resulting in heating of the stratosphere. The ozone layer is at an altitude between 10-15 miles (15-25 km). Approximately 90 % of the ozone in the atmosphere resides in the stratosphere. Ozone concentration in the this region is about 10 parts per million by volume (ppmv) as compared to approximately 0.04 ppmv in the troposphere. Ozone absorbs the bulk of solar ultraviolet radiation in wavelengths from 290 nm - 320 nm (UV-B radiation). These wavelengths are harmful to life because they can be absorbed by the nucleic acid in cells. Increased penetration of ultraviolet radiation to the planet's surface would damage plant life and have harmful environmental consequences. Appreciably large amounts of solar ultraviolet radiation would result in a host of biological effects, such as a dramatic increase in cancers.
The word mesosphere (from the Greek words
mesos = middle and sphaira = ball) which is third layer of the earth just below Thermosphere and above Stratosphere layer, staring from the ground, from about 45-50 Km (28-32 miles) to 80-85 Km (50-53 miles) of height. The temperature of mesophere decreases with increase in height.The anomalous propagation of sound refers to the downward refraction of an oblique sound wave an explosion, the refraction occurring in the region of increasing temperature with height in the lower
mesosphere. The temperature in this layer be as low as 200K( -73° C, -99° F), varying according to latitude and season. Millions of meteors burn up daily in the mesosphere, as a result of collisions with the gas particles contained there, leading to a high concentration of iron and metal atoms. The collisions almost always create enough heat to burn the falling objects long before they reach the ground. Thus the mesosphere protects the Earth from a barrage of would-be meteorites. mesosphere and stratosphere is regarded as the middle layer and from thermosphere it is regarded as the upper layer. the mesosphere and thermosphere is separated by the
mesopause, at an altitude of about 80 km. which lies near the turbopause .
The word
thermo refers to heat. It is the fourth layer of atmosphere as well as the biggest layer above the mesosphere and below exosphere. It extent from about 85-640 km above the earth . At these altitude, the residual atmospheric gases sort into strata according to molecular mass. Temperature in this layer increases with increase in altitude and can reach up to 1200C at a time due to absorption of highly energetic solar radiation by the small amount of residual oxygen present. However, even though the temperature is high one would not feel hot in the thermosphere as it is near the vacuum of deep space due to low density of gas atoms there.
Exosphere is the last layer of earth atmosphere. The
exosphere (from the Greek word
exo = out or outside) is the uppermost layer of the atmosphere. Its lower boundary at the edge of the thermosphere is estimated to be 500 km to 1,000 km above the Earth's surface, and its upper boundary at about 10,000 km. It is only from the exosphere that atmospheric
gases can, to any appreciable extent, escape into outer space. The main gases in the exosphere are the lightest ones, mainly
hydrogen and
helium, with some atomic oxygen near the exobase (the lowest altitude of the exosphere). The few particles of gas here can reach 2,500° C (4,500° F) during the day. The atmosphere in this layer is sufficiently rarified for
satellites to orbit the Earth, although they still receive some atmospheric drag. The exact altitude at which the exosphere ends and space begins is not well-defined, and attempting to attach a specific value to it is not particularly useful.
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