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Looking Back at Atmospheric Structure \(\PageIndex{1}\) If we examine the vertical structure the atmosphere in different places we will find it varies in height, being lowest at the poles and highest at the equator. The varying height is due to the spatial variation in heating of the Earth's surface and thus the atmosphere above.
A 1-cm 2 cross section of the earth’s surface supports a column weighing 1030 g; the total mass of the atmosphere is about 5.27 x 10 21 g. About 80% of the mass of the atmosphere resides in the first 10 km; this well-mixed region of fairly uniform composition is known as the troposphere. Solar irradiation of the Earth.
Composition and Structure of the Atmosphere. Atmosphere refers to the layer of gases that surrounds Earth and is held in place by Earth’s gravitational attraction (gravity). The mix of gases in the atmosphere forms a complex system organized into layers that together support life on Earth.
This chapter constitutes basic concepts of the atmospheric structure in the lower and middle atmosphere and composition of air. An effort is made to understand the changes in temperature in the troposphere and stratosphere.
- Overview
- Key points
Review your understanding of the composition and layers of Earth's atmosphere in this free article aligned to AP standards.
•Earth is surrounded by a mixture of gases called the atmosphere. The composition of the atmosphere is 78% nitrogen and 21% oxygen, with the remaining 1% consisting of water vapor, argon, carbon dioxide, and small amounts of other gases.
•Earth’s atmosphere consists of five distinct layers that are distinguished by temperature gradients—the layers alternate between having temperatures that increase or decrease with altitude. The five principal layers of the atmosphere are the troposphere, stratosphere, mesosphere, thermosphere, and exosphere.
•Troposphere: The troposphere is the layer closest to Earth. It is the densest layer (i.e., contains the most air particles), and is where most of Earth’s weather and cloud formation occurs. The troposphere is heated primarily by energy from the sun radiating off the Earth’s surface. This, along with the decrease in pressure that occurs with altitude, means that the troposphere has a temperature gradient that decreases with altitude.
•Stratosphere: The stratosphere is the layer above the troposphere. It has a concentrated region of ozone gas called the ozone layer, which keeps about 95% of the sun's harmful UV radiation from reaching the Earth’s surface. Ozone molecules absorb UV radiation and release heat, which causes the stratosphere to have a temperature gradient that increases with altitude.
•Mesosphere: The mesosphere is the layer above the stratosphere. The mesosphere is heated primarily by the stratosphere below, so it has a temperature gradient that decreases with altitude. The mesosphere is one of the coldest places on Earth. The average temperature is around minus 85° C (−120° F)!
•Thermosphere: The thermosphere is the layer above the mesosphere. It has a very low density of gas molecules. These molecules absorb highly energetic radiation from the sun, so the thermosphere has a temperature gradient that increases with altitude.
Atmospheric structure can be understood as resulting from the interplay of forces affecting the bulk structure (gravity, fluid motions), the conservation of energy (accounting for sources, sinks, and transport), and atmospheric composition (chemistry, opacity).
15 de may. de 2024 · atmosphere, the gas and aerosol envelope that extends from the ocean, land, and ice -covered surface of a planet outward into space.
