What is the Mesosphere?
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The mesosphere is the third layer of Earth’s atmosphere, located directly above the stratosphere and below the thermosphere. Although it is one of the lesser-known atmospheric layers, the mesosphere plays a vital role in protecting the Earth and is home to some of the most extreme conditions found in the atmosphere.
Location and Temperature
The mesosphere begins at about 50 kilometers (31 miles) above Earth’s surface and extends to approximately 85 kilometers (53 miles). It sits above the stratopause (the boundary between the stratosphere and mesosphere) and ends at the mesopause, which marks the coldest part of the Earth’s atmosphere.
One of the most important characteristics of the mesosphere is its decreasing temperature with altitude. Unlike the stratosphere, where temperature increases with height due to ozone absorption of ultraviolet radiation, the mesosphere gets colder the higher you go. At the mesopause, temperatures can drop to -90°C (-130°F) or lower, making it the coldest layer in the entire atmosphere.
Functions and Phenomena
The mesosphere may not contain weather systems like the troposphere, but it has its own set of important functions and unique phenomena:
- Meteor Protection: The mesosphere is often referred to as the “shield of Earth” because it is where most meteoroids burn up upon entering the atmosphere. When you see a shooting star, you are witnessing a meteoroid being vaporized in this layer due to friction with the atmospheric gases.
- Atmospheric Mixing: The mesosphere is a region of strong atmospheric circulation. It plays a role in redistributing energy and momentum between lower and upper atmospheric layers.
- Noctilucent Clouds: Near the mesopause, especially during the summer months at high latitudes, extremely rare and bright noctilucent clouds may form. These clouds are composed of ice crystals and are visible just after sunset or before sunrise.
Air Composition and Pressure
Although the mesosphere contains the same basic gases (mainly nitrogen and oxygen) found in the lower layers, the air density is much lower. In fact, the air pressure in the mesosphere is only about 1/1000th of the pressure at sea level. This makes the air so thin that it would be impossible to breathe without a pressurized suit.
Because the atmosphere is so rarefied, scientific instruments must be specially designed to withstand the conditions and collect accurate data. The mesosphere is too high for weather balloons to reach and too low for most satellites, making it one of the least explored layers of the atmosphere.
The Mesopause
The mesopause, which marks the upper boundary of the mesosphere and the beginning of the thermosphere, is notable for its extremely low temperatures. It serves as a transitional zone between two vastly different regions—one dominated by cold, thin air and the other by the intense heat of the thermosphere.
Why It’s Important
Even though we don’t experience the mesosphere directly, this layer is critical for life on Earth:
- It burns up meteoroids before they can hit the surface.
- It plays a role in atmospheric tides and global circulation patterns.
- It marks the boundary between Earth’s lower atmosphere (which supports life) and the more dangerous upper regions filled with radiation.
In short, the mesosphere acts as a barrier, a filter, and a dynamic buffer zone, connecting the lower, weather-forming atmosphere with the outermost, space-facing layers.
Timeline: Key Discoveries and Events Related to the Mesosphere
| Date | Event |
| 1889 | First use of sounding balloons (weather balloons) begins, providing indirect data on upper atmosphere layers, including the mesosphere. |
| 1902 | Scientist Léon Teisserenc de Bort discovers the stratosphere and theorizes the presence of an upper cold layer—what we now call the mesosphere. |
| 1950s | High-altitude rocket experiments begin during the Cold War, allowing the first direct measurements of the mesosphere. |
| 1960s | NASA satellites begin collecting more data about upper atmospheric temperature and pressure, confirming the structure of the mesosphere. |
| 1980s | Discovery and study of noctilucent clouds, revealing unique weather-like activity at the mesopause. |
| 2000s–Present | Continued satellite observation and computer modeling enhance our understanding of mesosphere’s role in global atmospheric circulation and climate science. |
Frequently Asked Questions
What is the mesosphere?
The mesosphere is the third layer of Earth’s atmosphere, located above the stratosphere and below the thermosphere. It extends from about 50 km to 85 km above Earth’s surface and is known for its extremely cold temperatures and role in burning up meteoroids.
Why is the mesosphere so cold?
The mesosphere gets colder with altitude because it lacks the ozone layer that warms the stratosphere below. It also receives very little solar radiation, and the thin air cannot retain heat effectively.
What happens to meteoroids in the mesosphere?
Meteoroids entering Earth’s atmosphere typically burn up in the mesosphere due to friction with the thin gases, creating bright trails of light known as “shooting stars.”
Can weather balloons or satellites study the mesosphere?
Not directly. Weather balloons don’t reach high enough, and most satellites orbit above it, making the mesosphere one of the least explored atmospheric layers. Scientists rely on rockets and remote sensing to study it.
What is the mesopause?
The mesopause is the boundary between the mesosphere and thermosphere. It marks the coldest point in Earth’s atmosphere, where temperatures can drop below -90°C (-130°F).
Does the mesosphere have any clouds?
Yes, but very rare ones called **noctilucent clouds** can form near the mesopause. These ice-crystal clouds glow at twilight and are usually visible from high latitudes in summer.
Why is the mesosphere important to life on Earth?
The mesosphere protects Earth by vaporizing meteors before they hit the surface. It also plays a role in atmospheric tides and energy transfer between layers.
What gases are found in the mesosphere?
The mesosphere contains mostly nitrogen and oxygen, just like the lower atmosphere, but the air is much thinner and not breathable without a pressurized suit.
How do we study the mesosphere if it’s so hard to reach?
Scientists use sounding rockets, remote sensors, radar, and satellite data to gather indirect measurements of temperature, wind, and pressure in the mesosphere.
Is there any weather in the mesosphere?
While traditional weather systems like rain and storms don’t occur in the mesosphere, it does have atmospheric waves, tides, and rare cloud formations that resemble weather activity.