Air Geography: Atmospheric Layers

• Air geography studies the spatial distribution and characteristics of atmospheric phenomena.
• Geographic factors influence weather patterns, climate zones, and air quality.
• Atmospheric Layers are distinct horizontal layers in the atmosphere with varying temperatures, densities, and compositions.

Troposphere

• The troposphere is the lowest layer, extending from the Earth's surface up to about 8-14.5 kilometers (5-9 miles).
• It contains most of the atmosphere's mass (around 75-80%) and water vapor.
• This layer is where weather occurs, including clouds, precipitation, and wind.
• Temperature generally decreases with altitude in the troposphere, at an average rate of 6.5°C per kilometer (environmental lapse rate).
• The upper boundary of the troposphere is called the tropopause.

Stratosphere

• The stratosphere lies above the troposphere, extending from the tropopause to about 50 kilometers (31 miles).
• It contains the ozone layer, which absorbs a significant amount of ultraviolet (UV) radiation from the Sun.
• Temperature generally increases with altitude in the stratosphere due to the absorption of UV radiation by ozone.
• The stratosphere is relatively stable, with little vertical mixing.
• The upper boundary of the stratosphere is called the stratopause.

Mesosphere

• The mesosphere is above the stratosphere, extending from the stratopause to about 85 kilometers (53 miles).
• Temperature decreases with altitude in the mesosphere, reaching the coldest temperatures in the atmosphere (around -90°C or -130°F) at the mesopause.
• Meteors burn up in the mesosphere.
• The upper boundary of the mesosphere is called the mesopause.

Thermosphere

• The thermosphere is above the mesosphere, extending from the mesopause to about 500-1,000 kilometers (311-621 miles).
• Temperature increases with altitude in the thermosphere due to absorption of highly energetic solar radiation.
• The thermosphere is characterized by very thin air.
• The ionosphere is located within the thermosphere.
• Auroras (Northern and Southern Lights) occur in the thermosphere.
• The upper boundary of the thermosphere is called the thermopause.

Exosphere

• The exosphere is the outermost layer of the atmosphere, extending from the thermopause outwards into space.
• It is a transitional zone between the Earth's atmosphere and outer space.
• The air is extremely thin in the exosphere, with molecules moving freely along ballistic trajectories.
• There is no clear upper boundary to the exosphere.

Ionosphere

• The ionosphere is a region within the thermosphere and mesosphere containing ions and free electrons.
• It is created by solar radiation ionizing gas molecules.
• The ionosphere plays a role in radio wave propagation, allowing long-distance communication.
• Auroras occur within the ionosphere.