atmosphere - Atmospheric Structure The gaseous area...

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Atmospheric Structure The gaseous area surrounding the planet is divided into several concentric strata or layers. About 99% of the total atmospheric mass is concentrated in the first 20 miles (32 km) above Earth's surface. Historical outline on the discovery of atmospheric structure. THERMAL STRUCTURE Atmospheric layers are characterized by variations in temperature resulting primarily from: 1. the absorption of solar radiation; 2. visible light at the surface; 3. near ultraviolet radiation in the middle atmosphere; 4. far ultraviolet radiation in the upper atmosphere. Troposphere 1. The troposphere is the atmospheric layer closest to the planet and contains the largest percentage (around 80%) of the mass of the total atmosphere. 2. Temperature and water vapor content in the troposphere decrease rapidly with altitude . 3. Water vapor plays a major role in regulating air temperature because it absorbs solar energy and thermal radiation from the planet's surface .
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4. The troposphere contains 99 % of the water vapor in the atmosphere. 5. Water vapor concentrations vary with latitude. 6. They are greatest above the tropics, where they may be as high as 3 %, and decrease toward the Polar Regions. 7. 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. 8. The upper boundary of the layer, known as the tropopause , 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. Stratosphere 1. The stratosphere is the second major strata of air in the atmosphere. It extends above the tropopause to an altitude of about 30 miles (50 km) above the planet's surface. 2. The air temperature in the stratosphere remains relatively constant up to an altitude of 15 miles (25 km). Then it increases gradually to up to the stratopause . Because the air temperature in the stratosphere increases with altitude, it does not cause convection and has a stabilizing effect on atmospheric conditions in the region. 3. Ozone plays the major role in regulating the thermal regime of the stratosphere, as water vapor content within the layer is very low . 4. 4. Temperature increases with ozone concentration. 5. 5. Solar energy is converted to kinetic energy when ozone molecules absorb ultraviolet radiation, resulting in heating of the stratosphere. OZONE LAYER 6. The ozone layer is centered at an altitude between 10-15 miles (15-25 km). 7. Approximately 90 % of the ozone in the atmosphere resides in the stratosphere. 8.
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atmosphere - Atmospheric Structure The gaseous area...

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