Troposphere vs. Exosphere — What's the Difference?
By Maham Liaqat & Fiza Rafique — Updated on March 26, 2024
The troposphere is the lowest layer of Earth's atmosphere, where weather occurs and air is densest, while the exosphere is the outermost layer, where air is extremely thin and molecules escape into space.
Difference Between Troposphere and Exosphere
Table of Contents
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Key Differences
The troposphere is the lowest layer of Earth's atmosphere, extending from the Earth's surface up to about 8 to 15 kilometers (5 to 9 miles). This layer contains about 75% of the atmosphere's mass and is where all weather conditions occur, from rain to snow to storms. On the other hand, the exosphere is the outermost layer of Earth's atmosphere, starting at about 600 kilometers (372 miles) above the Earth and extending up to 10,000 kilometers (6,200 miles) or even beyond. The exosphere is where the atmosphere thins out into space, and air molecules can escape into space.
In the troposphere, the temperature generally decreases with altitude, dropping about 6.5 degrees Celsius for every kilometer (or about 3.6 degrees Fahrenheit for every 1,000 feet) you go up. This temperature gradient is a result of the heating of the Earth's surface by the sun. Conversely, in the exosphere, temperature measurement becomes less meaningful because of the extremely low density of air molecules; however, those few molecules can achieve very high speeds and kinetic temperatures.
The air pressure in the troposphere decreases with altitude, from the highest pressure at sea level to much lower pressure at the top of the troposphere. This gradient is significant for the breathing of living organisms and the flight of aircraft. In contrast, the exosphere has virtually no air pressure because the air molecules are so sparse and occasionally escape into space.
Weather phenomena, including the formation of clouds, precipitation, and storms, occur exclusively within the troposphere due to its dense air composition and water vapor content. Meanwhile, the exosphere lacks the necessary conditions for weather, as it contains very few particles that are far apart, preventing any form of weather as experienced closer to the Earth's surface.
The troposphere is bounded above by the tropopause, a boundary marked by a temperature inversion or at least a point where the temperature lapse rate decreases significantly. Above the exosphere, there is no clear boundary as it gradually fades into the vacuum of space, making it difficult to define its upper limit precisely.
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Comparison Chart
Location
Lowest layer, up to 8-15 km above Earth's surface.
Outermost layer, starting at about 600 km above Earth.
Contains
75% of the atmosphere's mass, all weather conditions.
Extremely thin air, air molecules can escape into space.
Temperature Gradient
Decreases with altitude.
High kinetic temperatures due to sparse molecules.
Air Pressure
Decreases with altitude, highest at sea level.
Virtually no air pressure.
Weather Phenomena
All weather occurs in this layer.
No weather phenomena occur.
Upper Boundary
Tropopause
Gradually fades into the vacuum of space.
Compare with Definitions
Troposphere
Air pressure is highest at sea level.
The troposphere's air pressure supports human and animal life.
Exosphere
The outermost layer of Earth's atmosphere.
Satellites orbit within the exosphere.
Troposphere
Bounded above by the tropopause.
The tropopause acts as a cap, limiting weather to the troposphere.
Exosphere
Contains thin, sparse air molecules.
The exosphere's air is too thin to breathe.
Troposphere
The lowest atmospheric layer where weather occurs.
Clouds form in the troposphere due to water vapor condensing.
Exosphere
Temperature concepts differ due to low density.
Despite high kinetic temperatures, the exosphere feels cold.
Troposphere
Temperature decreases with altitude.
Climbing higher in the troposphere, you'll feel the air get colder.
Exosphere
Fades into the vacuum of space.
The exosphere gradually transitions into outer space.
Troposphere
Contains most of the atmospheric mass.
The troposphere holds about 75% of Earth's atmospheric mass.
Exosphere
Virtually no air pressure.
The exosphere's lack of air pressure means molecules can escape into space.
Troposphere
The lowest atmospheric layer; from 4 to 11 miles high (depending on latitude)
Exosphere
The exosphere (Ancient Greek: ἔξω éxō "outside, external, beyond", Ancient Greek: σφαῖρα sphaĩra "sphere") is a thin, atmosphere-like volume surrounding a planet or natural satellite where molecules are gravitationally bound to that body, but where the density is so low that the molecules are essentially collisionless. In the case of bodies with substantial atmospheres, such as Earth's atmosphere, the exosphere is the uppermost layer, where the atmosphere thins out and merges with outer space.
Troposphere
The troposphere is the first layer of the atmosphere of the Earth, and contains 75% of the mass of the planetary atmosphere and 99% of the total mass of water vapour and aerosols, and is where most weather phenomena occur. The average height of the troposphere is 18 km (11 mi; 59,000 ft) in the tropics, 17 km (11 mi; 56,000 ft) in the middle latitudes, and 6 km (3.7 mi; 20,000 ft) in the polar regions in winter; thus, the total average height of the troposphere is 13 km (8.1 mi; 43,000 ft).
Exosphere
The outermost region of a planet's atmosphere.
Troposphere
The lowest region of the atmosphere between the earth's surface and the tropopause, characterized by decreasing temperature with increasing altitude.
Exosphere
The outermost region of the earth's atmosphere, lying above the thermosphere and extending thousands of kilometers into space, from which molecules having sufficient velocity can escape the earth's gravitation.
Troposphere
The lower levels of the atmosphere extending from the surface of the Earth or another celestial body up to the tropopause. It is characterized by convective air movements and a large vertical temperature change.
Exosphere
The uppermost layer of a planet's atmosphere
Exosphere
An extremely thin atmosphere, as on Saturn's moon Dione
Exosphere
The outermost atmospheric layer
Common Curiosities
Why does temperature decrease in the troposphere?
Temperature decreases with altitude in the troposphere due to the decrease in solar heating from the Earth's surface upwards.
Can weather occur in the exosphere?
No, the exosphere lacks the necessary air density and water vapor for weather to occur.
What defines the troposphere?
The troposphere is defined as the lowest layer of Earth's atmosphere, where all weather phenomena occur.
How high does the troposphere extend?
It extends up to about 8 to 15 kilometers (5 to 9 miles) above Earth's surface.
What is unique about the exosphere?
The exosphere is the outermost atmospheric layer where air molecules can escape into space.
What is the temperature like in the exosphere?
While molecules in the exosphere can have high kinetic temperatures, the overall temperature concept is less meaningful due to the sparse air.
How does air pressure change between the troposphere and exosphere?
Air pressure is highest at sea level in the troposphere and virtually non-existent in the exosphere.
Can humans survive in the exosphere?
No, the exosphere's extremely low air pressure and lack of oxygen make it inhospitable for human life.
What role does the troposphere play in Earth's climate?
The troposphere is integral to Earth's climate system, hosting weather patterns that distribute heat and moisture globally.
Where do satellites orbit in relation to Earth's atmosphere?
Many satellites orbit within the exosphere.
What happens at the boundary between the troposphere and the next atmospheric layer?
The tropopause, marking this boundary, features a temperature inversion or stabilization, limiting weather to the troposphere.
How do scientists define the upper limit of the exosphere?
The upper limit of the exosphere isn't precisely defined, as it gradually fades into the vacuum of space.
Is the troposphere important for life on Earth?
Yes, the troposphere contains the air we breathe and is crucial for Earth's weather systems.
How does the thickness of the air vary between the troposphere and exosphere?
The air is densest in the troposphere and becomes exceedingly thin in the exosphere.
Do air molecules in the exosphere stay there permanently?
No, air molecules in the exosphere can gain enough velocity to escape into space.
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Written by
Maham Liaqat
Co-written by
Fiza RafiqueFiza Rafique is a skilled content writer at AskDifference.com, where she meticulously refines and enhances written pieces. Drawing from her vast editorial expertise, Fiza ensures clarity, accuracy, and precision in every article. Passionate about language, she continually seeks to elevate the quality of content for readers worldwide.
