Atmospheric temperature is a measure of

temperature Temperature is a physical quantity that expresses quantitatively the perceptions of hotness and coldness. Temperature is measured with a thermometer. Thermometers are calibrated in various temperature scales that historically have relied o ...

at different levels of the

Earth's atmosphere The atmosphere of Earth is the layer of gases, known collectively as air, retained by Earth's gravity that surrounds the planet and forms its planetary atmosphere. The atmosphere of Earth protects life on Earth by creating pressure allowing fo ...

. It is governed by many factors, including incoming solar radiation,

humidity Humidity is the concentration of water vapor present in the air. Water vapor, the gaseous state of water, is generally invisible to the human eye. Humidity indicates the likelihood for precipitation, dew, or fog to be present. Humidity dep ...

and

altitude Altitude or height (also sometimes known as depth) is a distance measurement, usually in the vertical or "up" direction, between a reference datum and a point or object. The exact definition and reference datum varies according to the context ...

. When discussing surface air temperature, the annual

atmospheric temperature range In meteorology, diurnal temperature variation is the variation between a high air temperature and a low temperature that occurs during the same day. Temperature lag Temperature lag is an important factor in diurnal temperature variation: peak d ...

at any geographical location depends largely upon the type of

biome A biome () is a biogeographical unit consisting of a biological community that has formed in response to the physical environment in which they are found and a shared regional climate. Biomes may span more than one continent. Biome is a broader ...

, as measured by the

Köppen climate classification The Köppen climate classification is one of the most widely used climate classification systems. It was first published by German-Russian climatologist Wladimir Köppen (1846–1940) in 1884, with several later modifications by Köppen, nota ...

Temperature versus altitude

] Temperature varies greatly at different heights relative to

Earth Earth is the third planet from the Sun and the only astronomical object known to harbor life. While large volumes of water can be found throughout the Solar System, only Earth sustains liquid surface water. About 71% of Earth's sur ...

's surface and this variation in temperature characterizes the four layers that exist in the atmosphere. These layers include the

troposphere The troposphere is the first and lowest layer of the atmosphere of the Earth, and contains 75% of the total mass of the planetary atmosphere, 99% of the total mass of water vapour and aerosols, and is where most weather phenomena occur. Fro ...

stratosphere The stratosphere () is the second layer of the atmosphere of the Earth, located above the troposphere and below the mesosphere. The stratosphere is an atmospheric layer composed of stratified temperature layers, with the warm layers of air h ...

mesosphere The mesosphere (; ) is the third layer of the atmosphere, directly above the stratosphere and directly below the thermosphere. In the mesosphere, temperature decreases as altitude increases. This characteristic is used to define its limits: it ...

, and

thermosphere The thermosphere is the layer in the Earth's atmosphere directly above the mesosphere and below the exosphere. Within this layer of the atmosphere, ultraviolet radiation causes photoionization/photodissociation of molecules, creating ions; the ...

. The troposphere is the lowest of the four layers, extending from the surface of the Earth to about into the atmosphere where the tropopause (the boundary between the troposphere stratosphere) is located. The width of the troposphere can vary depending on latitude, for example, the troposphere is thicker in the tropics (about ) because the tropics are generally warmer, and thinner at the poles (about ) because the poles are colder. Temperatures in the atmosphere decrease with height at an average rate of 6,5°C (11,7 °F) per kilometer. Because the troposphere experiences its warmest temperatures closer to Earth's surface, there is great vertical movement of heat and water vapour, causing turbulence. This turbulence, in conjunction with the presence of water vapour, is the reason that weather occurs within the troposphere. Following the tropopause is the stratosphere. This layer extends from the tropopause to the stratopause which is located at an altitude of about . Temperatures remain constant with height from the tropopause to an altitude of , after which they start to increase with height. This happening is referred to as an

inversion Inversion or inversions may refer to: Arts * , a French gay magazine (1924/1925) * ''Inversion'' (artwork), a 2005 temporary sculpture in Houston, Texas * Inversion (music), a term with various meanings in music theory and musical set theory * ...

and It is because of this inversion that the stratosphere is not characterised as turbulent. The stratosphere receives its warmth from the sun and the ozone layer which absorbs ultraviolet radiation. The next layer is called the mesosphere which extends from the stratopause to the mesopause, located at an altitude of . Temperatures in the mesosphere decrease with altitude and are in fact the coldest in the Earth's atmosphere This decrease in temperature can be attributed to the diminishing radiation received from the Sun, after most of it has already been absorbed by the thermosphere. The fourth layer of the atmosphere is known as the thermosphere which extends from the mesopause to the 'top' of the collisional atmosphere. Some of the warmest temperatures can be found in the

, due to its reception of strong

ionizing radiation Ionizing radiation (or ionising radiation), including nuclear radiation, consists of subatomic particles or electromagnetic waves that have sufficient energy to ionize atoms or molecules by detaching electrons from them. Some particles can travel ...

at the level of the Van Allen radiation belt.

Temperature range

The variation in temperature that occurs from the highs of the day to the cool of nights is called

diurnal temperature variation In meteorology, diurnal temperature variation is the variation between a high air temperature and a low temperature that occurs during the same day. Temperature lag Temperature lag is an important factor in diurnal temperature variation: peak da ...

. Temperature ranges can also be based on periods of a month, or a year. The size of ground-level atmospheric temperature ranges depends on several factors, such as: * The average temperature * The average

* The regime of

wind Wind is the natural movement of air or other gases relative to a planet's surface. Winds occur on a range of scales, from thunderstorm flows lasting tens of minutes, to local breezes generated by heating of land surfaces and lasting a few ...

s (intensity, duration, variation, temperature, etc.) * The proximity to large bodies of

water Water (chemical formula ) is an inorganic, transparent, tasteless, odorless, and nearly colorless chemical substance, which is the main constituent of Earth's hydrosphere and the fluids of all known living organisms (in which it acts as ...

, such as the

sea The sea, connected as the world ocean or simply the ocean, is the body of salty water that covers approximately 71% of the Earth's surface. The word sea is also used to denote second-order sections of the sea, such as the Mediterranean Sea, ...

The figure at below-left shows an example of monthly temperatures recorded at one of such locations, the city of

Campinas Campinas (, ''Plains'' or ''Meadows'') is a Brazilian municipality in São Paulo State, part of the country's Southeast Region. According to the 2020 estimate, the city's population is 1,213,792, making it the fourteenth most populous Brazilian ...

state of São Paulo State may refer to: Arts, entertainment, and media Literature * ''State Magazine'', a monthly magazine published by the U.S. Department of State * ''The State'' (newspaper), a daily newspaper in Columbia, South Carolina, United States * ''Our S ...

Brazil Brazil ( pt, Brasil; ), officially the Federative Republic of Brazil (Portuguese: ), is the largest country in both South America and Latin America. At and with over 217 million people, Brazil is the world's fifth-largest country by area ...

, which lies approximately 60 km north of the Capricorn line (

latitude In geography, latitude is a coordinate that specifies the north– south position of a point on the surface of the Earth or another celestial body. Latitude is given as an angle that ranges from –90° at the south pole to 90° at the north ...

of 22 degrees). Average yearly temperature is 22.4 degrees Celsius, ranging from an average minimum of 12.2 degrees to a maximum of 29.9 degrees. The average temperature range is 11.4 degrees. Variability along the year is small (standard deviation of 2.31 for the maximum monthly average and 4.11 for the minimum). It is easy to see in the graph another typical phenomenon of temperature ranges, which is its increase during winter (lower average air temperature). In Campinas, for example, the daily temperature range in July (the coolest month of the year) may vary between typically 10 and 24 degrees Celsius (range of 14), while in January, it may range between 20 and 30 degrees Celsius (range of 10). The effect of latitude, tropical climate, constant gentle wind and sea-side locations show smaller average temperature ranges, smaller variations of temperature, and a higher average temperature (second graph, taken for the same period as Campinas, at

Aracaju Aracaju () is the capital of the state of Sergipe, Brazil, located in the northeastern part of the country on the coast, about 350 km (217 mi) north of Salvador. According to the 2020 estimate, the city has 664,908 inhabitants, which rep ...

, capital of the state of

Sergipe Sergipe (), officially State of Sergipe, is a state of Brazil. Located in the Northeast Region along the Atlantic coast of the country, Sergipe is the smallest state in Brazil by geographical area at , larger only than the Federal District. ...

, also in Brazil, at a latitude of 10 degrees, nearer to the

Equator The equator is a circle of latitude, about in circumference, that divides Earth into the Northern and Southern hemispheres. It is an imaginary line located at 0 degrees latitude, halfway between the North and South poles. The term can also ...

). Average maximum yearly temperature is 28.7 degrees Celsius and average minimum is 21.9. The average temperature range is 5.7 degrees only. Temperature variation along the year in Aracaju is very damped (standard deviation of 1.93 for the maximum temperature and 2.72 for the minimum temperature).

Significance

A location which combines an average temperature of 19 degrees Celsius, 60% average humidity and a temperature range of about 10 degrees Celsius around the average temperature (yearly temperature variation) is considered ideal in terms of comfort for the human species. Most of the places with these characteristics are located in the transition between temperate and tropical climates, approximately around the

tropics The tropics are the regions of Earth surrounding the Equator. They are defined in latitude by the Tropic of Cancer in the Northern Hemisphere at N and the Tropic of Capricorn in the Southern Hemisphere at S. The tropics are also refer ...

, particularly in the Southern hemisphere (the

tropic of Capricorn The Tropic of Capricorn (or the Southern Tropic) is the circle of latitude that contains the subsolar point at the December (or southern) solstice. It is thus the southernmost latitude where the Sun can be seen directly overhead. It also reac ...

Lifted minimum temperature

The minimum temperature on calm, clear nights has been observed to occur not on the ground, but rather a few tens of centimeters above the ground. The lowest temperature layer is called ''Ramdas layer'' after L. A. Ramdas, who first reported this phenomenon in 1932 based on observations at different screen heights at six meteorological centers across India. The phenomenon is attributed to the interaction of

thermal radiation Thermal radiation is electromagnetic radiation generated by the thermal motion of particles in matter. Thermal radiation is generated when heat from the movement of charges in the material (electrons and protons in common forms of matter) i ...

effects on atmospheric aerosols and

convection Convection is single or multiphase fluid flow that occurs spontaneously due to the combined effects of material property heterogeneity and body forces on a fluid, most commonly density and gravity (see buoyancy). When the cause of the c ...

transfer close to the ground.

Global temperature

The concept of a global temperature is commonly used in

climatology Climatology (from Greek , ''klima'', "place, zone"; and , '' -logia'') or climate science is the scientific study of Earth's climate, typically defined as weather conditions averaged over a period of at least 30 years. This modern field of stu ...

, and denotes the average temperature of the Earth based on surface, near-surface or

tropospheric The troposphere is the first and lowest layer of the atmosphere of the Earth, and contains 75% of the total mass of the planetary atmosphere, 99% of the total mass of water vapour and aerosols, and is where most weather phenomena occur. From t ...

measurements. These

temperature record The global temperature record shows the fluctuations of the temperature of the atmosphere and the oceans through various spans of time. There are numerous estimates of temperatures since the end of the Pleistocene glaciation, particularly dur ...

s and measurements are typically acquired using the

satellite A satellite or artificial satellite is an object intentionally placed into orbit in outer space. Except for passive satellites, most satellites have an electricity generation system for equipment on board, such as solar panels or radioiso ...

or ground instrumental temperature

measurements Measurement is the quantification of attributes of an object or event, which can be used to compare with other objects or events. In other words, measurement is a process of determining how large or small a physical quantity is as compared ...

, then usually compiled using a database or

computer model Computer simulation is the process of mathematical modelling, performed on a computer, which is designed to predict the behaviour of, or the outcome of, a real-world or physical system. The reliability of some mathematical models can be deter ...

. Long-term global temperatures in

paleoclimate Paleoclimatology (British spelling, palaeoclimatology) is the study of climates for which direct measurements were not taken. As instrumental records only span a tiny part of Earth's history, the reconstruction of ancient climate is important to ...

are discerned using proxy data.

References