Temperatures in the mesosphere fall as one ascends in altitude. The heat source is the stratosphere below because there are few gas molecules in the mesosphere to absorb the sun's rays. The mesosphere is exceedingly cold, especially at the summit, with temperatures hovering about -90 degrees Celsius (-130 degF).
The Earth's atmosphere can be divided into five major layers: ground level down to around 10-20 miles (20-40 km) above sea level; the troposphere, which extends from about 20 miles up to about 60 miles (100 km) high; the stratosphere, which begins at about 60 miles (100 km) height; the thermosphere, which reaches up to about 100 miles (160 km); and space.
Earth's atmosphere consists of three distinct regions -- the troposphere, the stratosphere, and the thermosphere -- that extend from ground level to space beyond our planet's surface.
The troposphere is where most weather occurs. It is the lowest layer of the atmosphere, extending from the earth's surface to about 18 miles (30 km). It is filled with air that has been rising and falling due to differences in temperature caused by solar energy reaching the surface. As warm air rises, it becomes less dense than the surrounding cooler air, so it floats away from its original location. Once high in the troposphere, this air will eventually reach equilibrium temperature with the surrounding air and then begin to descend.
Temperatures fall with altitude in the mesosphere. Near the top of this layer, the lowest temperatures in the Earth's atmosphere, around -90 °C (-130 °F), may be found. The mesopause is the border between the mesosphere and the thermosphere above it. The majority of meteors evaporate in the mesosphere.
The mesosphere is important for science and technology because it is here that many types of scientific experiments are conducted using satellites. Satellites used for meteorology, oceanography, climate change research, and resource management all operate in the mesosphere. In addition, the mesosphere is the location of the Van Allen radiation belts: regions of space dominated by electrons that surround the Earth.
The mesosphere is also relevant to humans because it is here that some types of high-altitude military operations take place. Stratofortresses and other large aircraft carriers conduct training missions into the mesosphere for missile evasion techniques. These exercises are called airborne laser targeting systems tests or ALTS tests. The pilots use telescopes to see ground targets below and monitor cameras to see any threats from above the plane. If a threat is detected, the pilots can climb or dive to evade it.
The mesosphere is located between 8 and 50 miles (13-80 km) up in the air. It has several different layers like the rest of the atmosphere but they are so thin that they do not affect weather or astronomy at these heights. The mesosphere is a dynamic environment.
The mesosphere is a layer of the middle atmosphere located between the stratosphere and the thermosphere (10–100 kilometers, 33,000–330,000 feet, 6.2–62 miles). The fall in temperature with height is caused by a reduction in solar heating from the stratosphere. The temperature is the coldest on Earth just below the mesopause. Beyond the mesopause at about 60 km (37 miles), temperatures continue to rise with altitude.
The mesosphere is important because it affects weather and climate on Earth. Some parts of the mesosphere are known as "frosty places," because they contain frozen gases that reflect sunlight away from Earth or form clouds that scatter it back toward space. These include the Föhn wind event, which occurs when a low-pressure system moves over a polar region causing freezing rain to fall near the surface. The resulting drop in air pressure can lead to collapsing buildings and injuries from falling objects. Frosty places are found almost everywhere on Earth where there is ice or snow on the ground during the winter months.
But most of the mesosphere isn't frosty. It contains molecules called nitric oxide and oxygen that block out much of the sun's heat energy. As these gases spread out across the sky, they create an ozone layer that protects living things from ultraviolet radiation. Countries like America and Russia produce enough nitrogen oxides into the atmosphere to keep the mesosphere free of ice.
Because the troposphere is heated by the earth, temperature falls with altitude. The troposphere is unstable because warm air rises and cool air sinks. Temperature rises with height in the stratosphere. The ozone layer, which protects the globe from the sun's damaging UV radiation, is found in the stratosphere.
Above the mesopause, which occurs at altitudes of 85–90 km (50–55 miles), temperature rises with altitude in a layer known as the thermosphere. The thermosphere's temperatures fluctuate from roughly 500 K (approximately 227 deg C, or 440 deg F) during periods of low sunspot activity to 2,000 K (1,725 deg C, or 3,137 deg F) when the sun is active. It is also worth mentioning that at some points during a solar storm the thermosphere can reach values as high as 4,500 K (3,400 deg C, or 7,200 deg F).
The average temperature of the thermosphere is about 1,100 K (1,095 deg C, or 1,085 deg F), but it can be as cold as 700 K (760 deg C, or 1,420 deg F) or as hot as 3,300 K (2,750 deg C, or 5,250 deg F). It should be noted that these are average values and that the actual temperature varies from place to place and even from moment to moment within a given location.
The human body produces around 95% oxygen and 5% carbon dioxide at normal temperatures. But at higher temperatures, more oxygen is needed so there is more oxygen in your blood. At very high temperatures, such as those experienced by astronauts on distant planets, there is no water vapor in the atmosphere to cool the planet down so life as we know it would not exist.
Unlike the stratosphere, temperatures continue to fall as you ascend into the mesosphere. At this altitude, there are no clouds or satellites to reflect sunlight back to space, so the temperature must drop due to radiation alone.
The lower part of the mesosphere is called the thermosphere. Here, temperatures rise again with increasing altitude. But even at the top of the thermosphere, which is about 50 miles (80 km) up, temperatures fall to about 600 degrees Fahrenheit (315 degrees Celsius).
This is because the thermosphere is a region where solar heat cannot compete with that of radioactive decay. Radioactive elements such as potassium and uranium disintegrate when exposed to light particles from the sun (rays). These particles can reach the upper levels of the atmosphere where they collide with other atoms leaving behind their energy state which can be converted into thermal energy.
The higher you go, the hotter it gets. By the time you reach the exosphere, temperatures exceed 5000 F (2500 C).
Here, there are no molecules except hydrogen atoms and electrons. The Earth's magnetic field protects us from some of the effects of radiation from the sun.