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The mesopause is the point of minimum temperature at the boundary between the mesosphere and the thermosphere atmospheric regions. Due to the lack of solar heating and very strong radiative cooling from carbon dioxide, the mesosphere is the coldest region on Earth with temperatures as low as -100 °C (-148 °F or 173 K). [1]
The mesosphere (/ ˈ m ɛ s ə s f ɪər, ˈ m ɛ z-, ˈ m iː s ə-,-z ə-/; [1] from Ancient Greek μέσος (mésos) 'middle' and -sphere) is the third layer of the atmosphere, directly above the stratosphere and directly below the thermosphere. In the mesosphere, temperature decreases as altitude increases.
Adiabatic processes for air have a characteristic temperature-pressure curve. As air circulates vertically, the air takes on that characteristic gradient. When the air contains little water, this lapse rate is known as the dry adiabatic lapse rate: the rate of temperature decrease is 9.8 °C/km (5.4 °F per 1,000 ft) (3.0 °C/1,000 ft). The ...
As a result, the lower mantle's temperature gradient as a function of depth is approximately adiabatic. [1] Calculation of the geothermal gradient observed a decrease from 0.47 kelvins per kilometre (0.47 °C/km; 1.4 °F/mi) at the uppermost lower mantle to 0.24 kelvins per kilometre (0.24 °C/km; 0.70 °F/mi) at 2,600 kilometres (1,600 mi). [3]
The MWP is generally thought to have occurred from about 950 CE to about 1250 CE, during the European Middle Ages. [2] Some researchers divide the MWP into two phases: MWP-I, which began around 450 CE and ended around 900 CE, and MWP-II, which lasted from about 1000 CE to about 1300 CE; MWP-I is called the early Medieval Warm Period while MWP-II is called the conventional Medieval Warm Period. [8]
The year 1816 is known as the Year Without a Summer because of severe climate abnormalities that caused average global temperatures to decrease by 0.4–0.7 °C (0.7–1 °F). [1] Summer temperatures in Europe were the coldest of any on record between 1766 and 2000, [ 2 ] resulting in crop failures and major food shortages across the Northern ...
Temperatures in the mesosphere decrease with altitude, and are the coldest in the Earth's atmosphere. [5] 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. [3]
The thermosphere (or the upper atmosphere) is the height region above 85 kilometres (53 mi), while the region between the tropopause and the mesopause is the middle atmosphere (stratosphere and mesosphere) where absorption of solar UV radiation generates the temperature maximum near an altitude of 45 kilometres (28 mi) and causes the ozone layer.