Atmospheric temperature

Atmospheric temperature is a way to measure how hot or cold it is at different heights in the Earth's atmosphere. This temperature changes because of many things, like how much sunlight reaches the Earth, how much water vapor is in the air, and how high above the ground you are. Scientists often use the term MAAT, which stands for Mean Annual Air Temperature, to talk about the average temperature of a place over a whole year.

Understanding atmospheric temperature helps us learn about weather patterns and climate. It affects everything from the clothes we wear to how plants grow. By studying these temperatures, scientists can better predict changes in our world and help protect the environment.

Near-surface air temperature

"Surface air temperature" redirects here; not to be confused with Soil temperature or Sea surface temperature.

For temperature measurements made by instruments, see Instrumental temperature record.

For temperature changes relevant to historical climate change over Earth's geologic past (distinguished from recent climate change), see Temperature record.

The temperature of the air close to Earth's surface is measured at weather stations using thermometers placed in special shelters, like a Stevenson screen. These thermometers are usually set 1.25–2 metres above the ground. The World Meteorological Organization has rules for how this should be done.

The average temperature near the Earth's surface worldwide is about 14 °C.

Temperature versus altitude

Main article: Lapse rate

The temperature in the atmosphere changes a lot depending on how high you go from the Earth's surface. The atmosphere has four main layers: the troposphere, stratosphere, mesosphere, and thermosphere.

The troposphere is the lowest layer, stretching from the ground up to about 11 kilometers. It's warmest near the ground and gets colder as you go higher. This layer is where most of our weather happens. Above the troposphere is the stratosphere, which gets warmer as you go higher because of special gases that protect the Earth from harmful sun rays. The mesosphere is the next layer, and it is the coldest part of the atmosphere. Finally, the thermosphere is the top layer and can get very hot because it receives strong energy from the sun.

Temperature range

The change in temperature from the warmest part of the day to the coolest part of the night is called diurnal temperature variation. We can also look at temperature changes over a month or a year.

The size of temperature changes near the ground depends on several things, such as:

• Average air temperature
• Average humidity
• The way winds behave
• How close we are to large bodies of water, like the sea

The picture on the left shows temperature records from the city of Campinas, Brazil. The average temperature there is 22.4 °C, with the coolest temperature usually around 12.2 °C and the warmest around 29.9 °C. In July, the temperature might change from about 10 °C to 24 °C, while in January it might change from about 20 °C to 30 °C.

In places closer to the Equator, like Aracaju, Brazil, the temperature changes are smaller. The average temperature there is higher, with the coolest temperature around 21.9 °C and the warmest around 28.7 °C.

Lifted minimum temperature

See also: Surface temperature inversion

On very quiet and clear nights, the coldest temperature is often found just a little bit above the ground, not right on it. This thin layer of cold air is called the Ramdas layer, named after a scientist who first noticed this in 1932. He studied temperatures at different heights at several weather stations in India. This happens because of how heat moves away from the ground and affects tiny particles in the air.

Global temperature

See also: Global surface temperature, Instrumental temperature record, Global temperature record, and Schumann resonances § Global temperature

In the study of weather and climate, global temperature means the average temperature of the Earth. Scientists find this by looking at temperature readings from satellites and instruments on the ground. They use these readings to build databases and computer models. To learn about temperatures from long ago, they look at clues from nature, called proxy data.