Mesothermal

In climatology, the term mesothermal is used to refer to certain forms of climate found typically in the Earth's temperate zones. It has a moderate amount of heat, with winters not cold enough to sustain snow cover. Summers are warm within oceanic climate regimes, and hot within continental climate regimes.

Origin of term[]

The term is derived from two Greek words meaning "having a moderate amount of heat." This can be misinterpreted, however, since the term is actually intended to describe only the temperature conditions that prevail during the winter months, rather than those for the year as a whole.

Definition[]

Under the original Köppen climate classification, all places with an average temperature in their coldest month that is colder than 18°C, but warmer than −3°C, are said to have a mesothermal climate. The isotherm of -3°C for the coldest monthly mean temperature, was observed to be the line where the climate was cold enough to support a fixed period of continuous snow cover every year.

In some climate classifications the isotherm of 0°C (32°F) for the coldest monthly mean temperature is observed as the line between mesothermal climates and microthermal climates where the coldest month has a mean temperature below -3°C.

Range[]

In the US, the northern boundary line between mesothermal and microthermal ranges is north of Juneau and Sitka along the margins of the Pacific Ocean. It then goes southeastward around about 42N latitude across the north-central US (not including mountain regions) then eastward across the lower Midwest to the East Coast near Boston. The southern boundary line between mesothermal and megathermal (or tropical) is across south Florida just above Palm Beach.

Summer[]

Summers in mesothermal climates may be hot (having an average temperature in their warmest month of 22 °C or above) or mild (with the warmest month averaging between 10 °C and 18 °C). The hot-summer, mesothermal climate is encountered exclusively in the Northern Hemisphere, in the landmass interiors of Asia and North America and along their east coasts, while the cool to mild summer climate is found along upper west coast and where oceanic climates are found.

List of mesothermal cities and their summer temperatures:
Hong Kong-hot summer
Los Angeles- hot summer
Milan-hot summer
New York City-hot summer
Tokyo-hot summer
London-warm summer
Mexico City-warm summer
Vancouver-warm summer

Moisture[]

In addition to being subdivisible by summer temperature, mesothermal climates can also be subclassified on the basis of precipitation — into humid, semiarid and arid subtypes within your front door within depth

References[]

Applied Climatology, John Griffiths (for use of 6 °C in the coldest month as poleward limit of subtropical climates) [1] [2]^{[permanent dead link]}