2.2 Vertical structure and layers of the atmosphere
5 min read•july 23, 2024
Earth's atmosphere is a complex system of layers, each with unique properties. The , where we live, experiences decreasing temperatures with height. Above it, the warms due to ozone, while the cools again.
The upper layers, including the and , play crucial roles in Earth's climate and space weather. These regions host phenomena like auroras and noctilucent clouds, and interact with solar radiation and particles, shaping our planet's environment.
Atmospheric Layers and Their Characteristics
Layers of Earth's atmosphere
Top images from around the web for Layers of Earth's atmosphere
Layers of the Atmosphere | Physical Geography View original
Is this image relevant?
sciencepage622 - The Five layers Of The Atmosphere-Andy View original
Is this image relevant?
atmosphere layers Archives - Universe Today View original
Is this image relevant?
Layers of the Atmosphere | Physical Geography View original
Is this image relevant?
sciencepage622 - The Five layers Of The Atmosphere-Andy View original
Is this image relevant?
1 of 3
Top images from around the web for Layers of Earth's atmosphere
Layers of the Atmosphere | Physical Geography View original
Is this image relevant?
sciencepage622 - The Five layers Of The Atmosphere-Andy View original
Is this image relevant?
atmosphere layers Archives - Universe Today View original
Is this image relevant?
Layers of the Atmosphere | Physical Geography View original
Is this image relevant?
sciencepage622 - The Five layers Of The Atmosphere-Andy View original
Is this image relevant?
1 of 3
- Troposphere
- Lowest layer extends from Earth's surface to an average height of 12 km (ranges from 8-18 km depending on latitude and season)
- Contains about 80% of the total mass of the atmosphere and almost all water vapor and
- Air pressure and density decrease rapidly with altitude
- Temperature decreases with height at an average rate of 6.5℃/km (known as the environmental ) due to adiabatic cooling as air expands and rises
- Stratosphere
- Extends from the (top of the troposphere) to an altitude of about 50 km
- Contains the which absorbs harmful ultraviolet (UV) radiation from the sun protecting life on Earth
- Temperature increases with altitude due to ozone absorbing UV radiation
- Very stable layer with little vertical mixing and low humidity
- Mesosphere
- Extends from the (top of the stratosphere) to an altitude of about 85 km
- Coldest layer with temperatures dropping to -90℃ at the (top of the mesosphere)
- Noctilucent clouds made of ice crystals can form near the mesopause during summer at high latitudes (visible at twilight)
- Most meteors burn up in the mesosphere due to friction with air molecules
- Thermosphere
- Extends from the mesopause to an altitude of about 600 km
- Temperature increases with height reaching up to 2000℃ due to absorption of intense solar radiation (UV and X-rays) by oxygen and nitrogen molecules
- Highly variable temperatures depending on solar activity
- Lower part of the thermosphere (80-550 km) is the ionosphere a region with high concentrations of ions and free electrons (important for radio wave propagation)
- Aurora (Northern and Southern Lights) occur in the thermosphere when energetic charged particles from the solar wind are guided by Earth's magnetic field and collide with air molecules
- Exosphere
- Uppermost layer above the thermosphere extending to about 10,000 km
- Extremely low density (atoms and molecules are so far apart they rarely collide)
- Atoms (mainly hydrogen and helium) can escape Earth's gravitational pull into space
- No clear upper boundary where the exosphere merges with interplanetary space
Temperature profile of atmosphere
- Temperature changes with altitude are determined by the balance between absorption and emission of radiation and energy transfer by and conduction
- Troposphere
- Solar radiation passes through and is absorbed by Earth's surface
- Earth's surface heats the lower troposphere by conduction and convection
- Greenhouse gases (water vapor, carbon dioxide) absorb outgoing infrared radiation emitted by Earth's surface further warming the lower troposphere
- Temperature decreases with height at an average rate of 6.5℃/km (environmental lapse rate) due to adiabatic cooling as air parcels expand and rise
- Stratosphere
- Temperature increases with altitude due to ozone absorbing solar UV radiation
- Ozone is produced by photochemical reactions involving oxygen molecules and UV radiation
- Positive lapse rate (temperature increasing with height) creates a stable layer with little vertical mixing
- Mesosphere
- Temperature decreases with altitude due to decreasing ozone concentration and reduced solar heating
- Coldest layer reaching -90℃ at the mesopause
- Thermosphere
- Temperature increases with altitude due to absorption of intense solar radiation (UV and X-rays) by oxygen and nitrogen molecules
- Highly variable temperatures (500-2000℃) depending on solar activity (higher during solar maximum)
Tropopause and Upper Atmospheric Layers
Role of tropopause
- The tropopause is the boundary between the troposphere and stratosphere
- Acts as a barrier to the vertical transport of air, moisture, and pollutants between the troposphere and stratosphere
- Tropopause height varies with latitude and season
- Higher in the tropics (16-18 km) where warm air rises to greater heights
- Lower in polar regions (8-10 km) where cold dense air sinks
- Higher in summer and lower in winter due to seasonal temperature changes
- Controls the vertical extent of weather systems (thunderstorms, hurricanes) by limiting convection to the troposphere
- Affects the exchange of greenhouse gases (water vapor, ozone) and pollutants between the troposphere and stratosphere impacting climate and air quality
- Changes in tropopause height and temperature can influence patterns and the development of extreme weather events
Features of upper atmospheric layers
- Mesosphere
- Noctilucent clouds form near the mesopause (85 km) in summer at high latitudes
- Composed of ice crystals that nucleate on meteoric dust particles
- Visible at twilight when illuminated by the sun below the horizon
- Most meteors ablate (burn up) in the mesosphere due to high-speed collisions with air molecules
- Meteor showers occur when Earth passes through the dusty trail of a comet
- Noctilucent clouds form near the mesopause (85 km) in summer at high latitudes
- Thermosphere
- Ionosphere (80-550 km) is a region with high concentrations of ions and free electrons
- Ionization caused by solar UV and X-ray radiation and energetic particle precipitation
- Divided into distinct layers (D, E, and F) based on electron density profiles
- Reflects radio waves enabling long-distance communication (AM radio, shortwave)
- Responsible for GPS signal delays and errors that must be corrected
- Aurora form when energetic electrons and protons guided by Earth's magnetic field collide with oxygen and nitrogen atoms and molecules causing them to emit light
- Colors depend on the type of atom/molecule and the energy of the collision (green from oxygen, red/blue from nitrogen)
- Auroral ovals centered around the geomagnetic poles (not the geographic poles)
- More intense and frequent during solar storms (coronal mass ejections, solar flares)
- Ionosphere (80-550 km) is a region with high concentrations of ions and free electrons
- Exosphere
- Transition zone between Earth's atmosphere and interplanetary space
- Extremely low density (particles rarely collide) allowing atoms to follow ballistic trajectories
- Lightest atoms (hydrogen and helium) can escape Earth's gravity into space
- Exosphere is supplied with atoms from the lower atmosphere and ions from the ionosphere
- Influenced by the solar wind (stream of charged particles from the sun) which can compress the exosphere on the dayside and create a geotail on the nightside
Key Terms to Review (22)
Adiabatic Processes: Adiabatic processes are thermodynamic changes in which no heat is exchanged between a system and its surroundings, allowing for changes in pressure and temperature solely due to work done on or by the system. These processes are crucial in understanding atmospheric behavior, including how air parcels rise and fall in the atmosphere, which ties into the principles of thermodynamics and the vertical structure of the atmosphere.
Aerosols: Aerosols are tiny particles or droplets suspended in the atmosphere that can affect climate, weather, and air quality. These particles originate from various sources such as natural processes, like volcanic eruptions and sea spray, as well as human activities like industrial emissions and vehicle exhaust. Aerosols play a crucial role in cloud formation, radiative transfer, and atmospheric chemistry.
Altitude Effect: The altitude effect refers to the changes in atmospheric conditions and physical processes that occur as elevation increases. These changes can significantly influence weather patterns, climate, and human physiology, as air pressure and temperature decrease with higher altitudes, affecting everything from the behavior of clouds to how living organisms adapt to their environments.
Barometric Pressure: Barometric pressure is the weight of the atmosphere above a specific point, usually measured in millibars (mb) or inches of mercury (inHg). This pressure decreases with altitude, affecting atmospheric density and temperature profiles, and plays a crucial role in determining weather patterns and climate conditions. Understanding barometric pressure helps explain how the atmosphere is structured vertically and how air behaves in different layers.
Convection: Convection is the process by which heat is transferred through the movement of fluids, including gases and liquids, due to differences in temperature and density. This movement creates circulation patterns that are crucial for various atmospheric phenomena, influencing weather systems, cloud formation, and precipitation. Understanding convection helps explain how air masses interact with each other, leading to changes in atmospheric stability and the development of storms.
Exosphere: The exosphere is the outermost layer of Earth's atmosphere, where the atmosphere transitions into outer space. It extends from about 600 kilometers (373 miles) above sea level to around 10,000 kilometers (6,200 miles) and is characterized by extremely low densities of particles. In this layer, atoms and molecules can escape into space, and it plays a critical role in satellite orbits and space exploration.
Humidity profile: A humidity profile is a vertical representation of the distribution of humidity in the atmosphere, typically illustrating how moisture content varies with altitude. Understanding the humidity profile is essential for meteorology as it impacts weather patterns, cloud formation, and precipitation processes. It is a crucial component when analyzing the vertical structure of the atmosphere and can be effectively observed using satellite technology.
Jet stream: A jet stream is a fast-flowing air current located high in the atmosphere, typically found near the tropopause, that significantly influences weather patterns and climate. These narrow bands of strong winds occur at altitudes of about 10 kilometers (33,000 feet) and can extend for thousands of kilometers, affecting both local and global atmospheric dynamics.
Lapse rate: Lapse rate is the rate at which temperature decreases with an increase in altitude within the atmosphere. This concept is crucial in understanding how temperature changes impact atmospheric density and pressure, influencing buoyancy and convection processes that drive weather patterns. By examining the lapse rate, one can gain insights into the vertical structure of the atmosphere and how it affects various meteorological phenomena.
Mesopause: The mesopause is the boundary layer that separates the mesosphere from the thermosphere in Earth's atmosphere, typically occurring at altitudes of about 85 to 100 kilometers above sea level. It is characterized by a decrease in temperature, reaching its coldest point at this layer, which plays a crucial role in atmospheric dynamics and chemical processes.
Mesosphere: The mesosphere is the third layer of Earth's atmosphere, located above the stratosphere and below the thermosphere, extending from about 50 to 85 kilometers above sea level. This layer is characterized by decreasing temperatures with altitude and is where most meteorites burn up upon entering Earth's atmosphere, creating bright streaks known as meteors.
Ozone layer: The ozone layer is a region of Earth's stratosphere that contains a high concentration of ozone (O₃) molecules, which absorb the majority of the sun's harmful ultraviolet (UV) radiation. This layer plays a crucial role in protecting life on Earth and is part of the overall atmospheric system, influencing various interactions between different atmospheric layers and processes.
Radiative heating in the stratosphere: Radiative heating in the stratosphere refers to the process by which solar radiation is absorbed by ozone and other trace gases, resulting in the warming of this atmospheric layer. This heating is crucial for understanding the vertical structure of the atmosphere, as it influences temperature distribution and stability within the stratosphere, ultimately affecting weather patterns and climate.
Radiosonde: A radiosonde is an instrument used to measure various atmospheric parameters, such as temperature, humidity, and pressure, while being carried aloft by a weather balloon. This device plays a vital role in capturing vertical profiles of the atmosphere, which are essential for understanding weather patterns and stability conditions.
Satellite observations: Satellite observations refer to the use of satellites equipped with remote sensing technology to collect data about the Earth's atmosphere, surface, and weather systems from space. This powerful tool allows for continuous monitoring and analysis of various atmospheric phenomena, making it essential for understanding the vertical structure of the atmosphere, severe weather events, forecasting, and improving numerical weather prediction models.
Stratopause: The stratopause is the boundary layer between the stratosphere and the mesosphere in the Earth's atmosphere, occurring at altitudes of about 50 kilometers (31 miles) above sea level. It represents a significant transition point where the temperature trend reverses from increasing in the stratosphere to decreasing in the mesosphere, marking a shift in atmospheric behavior and composition.
Stratosphere: The stratosphere is the second layer of Earth's atmosphere, situated above the troposphere and extending from about 10 to 50 kilometers in altitude. This layer is characterized by a temperature increase with altitude due to the absorption of ultraviolet (UV) radiation by ozone, which plays a crucial role in protecting life on Earth. The stratosphere's stability influences weather patterns and is essential for understanding atmospheric soundings, density and pressure profiles, and the overall vertical structure of the atmosphere.
Temperature Inversion: A temperature inversion occurs when the temperature increases with altitude, contrary to the typical decrease in temperature found in the atmosphere. This phenomenon can trap pollutants near the surface, significantly impacting air quality and weather patterns, and is crucial in understanding atmospheric stability, boundary layers, and pollution dispersion.
Thermosphere: The thermosphere is the layer of Earth's atmosphere that lies above the mesosphere and below the exosphere, extending from about 85 kilometers (53 miles) to 600 kilometers (373 miles) above sea level. This layer is characterized by a significant increase in temperature with altitude, caused by the absorption of high-energy solar radiation. The thermosphere plays a crucial role in atmospheric dynamics and is where phenomena like the auroras occur, linking it to broader interactions within Earth's atmospheric system.
Tropopause: The tropopause is the boundary layer between the troposphere and the stratosphere in Earth's atmosphere, typically found at an altitude of about 8 to 15 kilometers above sea level. This layer marks a significant change in temperature and atmospheric conditions, where the temperature generally stabilizes or increases with altitude instead of continuing to decrease, which is characteristic of the troposphere. The tropopause plays a crucial role in weather patterns and the distribution of atmospheric phenomena.
Troposphere: The troposphere is the lowest layer of Earth's atmosphere, extending from the surface up to about 8 to 15 kilometers in altitude, depending on geographical location and weather conditions. This layer is crucial as it contains most of the atmosphere's mass, including water vapor, and is where all weather phenomena occur, making it integral to understanding atmospheric processes and stability.
Weather formation in the troposphere: Weather formation in the troposphere refers to the processes that create various weather conditions, including temperature changes, precipitation, and wind patterns, occurring in the lowest layer of Earth's atmosphere. The troposphere is where most weather phenomena happen due to its proximity to the Earth's surface, where moisture and heat interact. Understanding how different air masses and atmospheric conditions come together helps explain the diversity of weather events experienced in this layer.