Megathermal
Encyclopedia
In climatology
, the term megathermal (or less commonly, macrothermal) is sometimes used as a synonym for "tropical."
In order for a particular place to qualify as having a megathermal climate, every single month out of the year must have an average temperature
of 18°C or above.
Megathermal climates are sometimes split into two temperature-based subsets — equatorial and tropical (the latter used here in the sense of "outer tropical") — with "equatorial" denoting little or no variation in temperature throughout the year and "tropical" denoting significant seasonal variation, even though no month has an average temperature of below 18°C. In addition, what temperature fluctuations do exist in an equatorial climate will typically bear no relationship to the astronomical seasons for the applicable side of the equator
, while in the (outer) tropical subtype the temperature will move in concert with the seasons, the time of higher sun and longer days being warmest and the time of lower sun and shorter days coolest.
These climates can also be subdivided on the basis of rainfall
, as examples of humid, semiarid and arid
places can all be found within the megathermal category (although the region of arid megathermal climate is small compared with the extent of deserts existing in other climate zones, particularly the neighboring subtropical zone).
Climatology
Climatology is the study of climate, scientifically defined as weather conditions averaged over a period of time, and is a branch of the atmospheric sciences...
, the term megathermal (or less commonly, macrothermal) is sometimes used as a synonym for "tropical."
In order for a particular place to qualify as having a megathermal climate, every single month out of the year must have an average temperature
Temperature
Temperature is a physical property of matter that quantitatively expresses the common notions of hot and cold. Objects of low temperature are cold, while various degrees of higher temperatures are referred to as warm or hot...
of 18°C or above.
Megathermal climates are sometimes split into two temperature-based subsets — equatorial and tropical (the latter used here in the sense of "outer tropical") — with "equatorial" denoting little or no variation in temperature throughout the year and "tropical" denoting significant seasonal variation, even though no month has an average temperature of below 18°C. In addition, what temperature fluctuations do exist in an equatorial climate will typically bear no relationship to the astronomical seasons for the applicable side of the equator
Equator
An equator is the intersection of a sphere's surface with the plane perpendicular to the sphere's axis of rotation and containing the sphere's center of mass....
, while in the (outer) tropical subtype the temperature will move in concert with the seasons, the time of higher sun and longer days being warmest and the time of lower sun and shorter days coolest.
These climates can also be subdivided on the basis of rainfall
Rain
Rain is liquid precipitation, as opposed to non-liquid kinds of precipitation such as snow, hail and sleet. Rain requires the presence of a thick layer of the atmosphere to have temperatures above the melting point of water near and above the Earth's surface...
, as examples of humid, semiarid and arid
Arid
A region is said to be arid when it is characterized by a severe lack of available water, to the extent of hindering or even preventing the growth and development of plant and animal life...
places can all be found within the megathermal category (although the region of arid megathermal climate is small compared with the extent of deserts existing in other climate zones, particularly the neighboring subtropical zone).