In climatology

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 mesothermal is used to refer to certain forms of climate

Climate

Climate encompasses the statistics of temperature, humidity, atmospheric pressure, wind, rainfall, atmospheric particle count and other meteorological elemental measurements in a given region over long periods...

 found typically in the Earth

Earth

Earth is the third planet from the Sun, and the densest and fifth-largest of the eight planets in the Solar System. It is also the largest of the Solar System's four terrestrial planets...

's Temperate Zones

Temperate

In geography, temperate or tepid latitudes of the globe lie between the tropics and the polar circles. The changes in these regions between summer and winter are generally relatively moderate, rather than extreme hot or cold...

. 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

Greek language

Greek is an independent branch of the Indo-European family of languages. Native to the southern Balkans, it has the longest documented history of any Indo-European language, spanning 34 centuries of written records. Its writing system has been the Greek alphabet for the majority of its history;...

 words meaning "having a moderate amount of heat." This can be misinterpreted, however, since the term is actually intended to describe only the 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...

 conditions that prevail during the winter months, rather than those for the year as a whole.

Definition

Under the broadest definition, 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. In some climate classification schemes, however, this is divided into two segments, with a coldest-month average of 6°C being the line of demarcation between them; then only those locations with a coldest-month temperature of between −3°C and 6°C are reckoned as mesothermal, the label "subtropical" being applied to areas where the average temperature in the coldest month ranges from 6°C to 18°C.

Observing the narrower definition articulated above, the mesothermal locations are those where the winters are too cold to allow year-round photosynthesis

Photosynthesis

Photosynthesis is a chemical process that converts carbon dioxide into organic compounds, especially sugars, using the energy from sunlight. Photosynthesis occurs in plants, algae, and many species of bacteria, but not in archaea. Photosynthetic organisms are called photoautotrophs, since they can...

, but not cold enough to support a fixed period of continuous snow

Snow

Snow is a form of precipitation within the Earth's atmosphere in the form of crystalline water ice, consisting of a multitude of snowflakes that fall from clouds. Since snow is composed of small ice particles, it is a granular material. It has an open and therefore soft structure, unless packed by...

 cover every year.

Range

In the USA, the boundary line between mesothermal and microthermal ranges is between Juneau and Sitka at the Pacific Ocean. It goes sharply south to about 38N latitude in the Rockies, and back up to around 40N latitude on the east coast. The border with the megathermal zone passes through Southern Florida.

Summer

Summers in these places may be hot (that is to say, having an average temperature in their warmest month of 22°C or above) or merely warm (with the warmest month averaging between 10°C and 22°C). The hot-summer, or continental, mesothermal climate is encountered exclusively in the Northern Hemisphere

Northern Hemisphere

The Northern Hemisphere is the half of a planet that is north of its equator—the word hemisphere literally means “half sphere”. It is also that half of the celestial sphere north of the celestial equator...

, in the landmass interiors of Asia

Asia

Asia is the world's largest and most populous continent, located primarily in the eastern and northern hemispheres. It covers 8.7% of the Earth's total surface area and with approximately 3.879 billion people, it hosts 60% of the world's current human population...

 and North America

North America

North America is a continent wholly within the Northern Hemisphere and almost wholly within the Western Hemisphere. It is also considered a northern subcontinent of the Americas...

 and along their east coasts, while the most frequently seen example of a warm-summer mesothermal climate is the oceanic climate

Oceanic climate

An oceanic climate, also called marine west coast climate, maritime climate, Cascadian climate and British climate for Köppen climate classification Cfb and subtropical highland for Köppen Cfb or Cwb, is a type of climate typically found along the west coasts at the middle latitudes of some of the...

s found along the west coasts of all of the world's continents, roughly equidistant between the geographical tropical and polar zones

Polar region

Earth's polar regions are the areas of the globe surrounding the poles also known as frigid zones. The North Pole and South Pole being the centers, these regions are dominated by the polar ice caps, resting respectively on the Arctic Ocean and the continent of Antarctica...

.

List of mesothermal cities and their summer temperatures:

Hong Kong

Hong Kong

Hong Kong is one of two Special Administrative Regions of the People's Republic of China , the other being Macau. A city-state situated on China's south coast and enclosed by the Pearl River Delta and South China Sea, it is renowned for its expansive skyline and deep natural harbour...

-hot summer

Milan

Milan

Milan is the second-largest city in Italy and the capital city of the region of Lombardy and of the province of Milan. The city proper has a population of about 1.3 million, while its urban area, roughly coinciding with its administrative province and the bordering Province of Monza and Brianza ,...

-hot summer

New York City

New York City

New York is the most populous city in the United States and the center of the New York Metropolitan Area, one of the most populous metropolitan areas in the world. New York exerts a significant impact upon global commerce, finance, media, art, fashion, research, technology, education, and...

-hot summer

Tokyo

Tokyo

, ; officially , is one of the 47 prefectures of Japan. Tokyo is the capital of Japan, the center of the Greater Tokyo Area, and the largest metropolitan area of Japan. It is the seat of the Japanese government and the Imperial Palace, and the home of the Japanese Imperial Family...

-hot summer

London

London

London is the capital city of :England and the :United Kingdom, the largest metropolitan area in the United Kingdom, and the largest urban zone in the European Union by most measures. Located on the River Thames, London has been a major settlement for two millennia, its history going back to its...

-warm summer

Mexico City

Mexico City

Mexico City is the Federal District , capital of Mexico and seat of the federal powers of the Mexican Union. It is a federal entity within Mexico which is not part of any one of the 31 Mexican states but belongs to the federation as a whole...

-warm summer

Vancouver

Vancouver

Vancouver is a coastal seaport city on the mainland of British Columbia, Canada. It is the hub of Greater Vancouver, which, with over 2.3 million residents, is the third most populous metropolitan area in the country,...

-warm summer

Moisture

In addition to being subdivisible by summer temperature, mesothermal climates can also be subclassified on the basis of precipitation

Precipitation (meteorology)

In meteorology, precipitation In meteorology, precipitation In meteorology, precipitation (also known as one of the classes of hydrometeors, which are atmospheric water phenomena is any product of the condensation of atmospheric water vapor that falls under gravity. The main forms of precipitation...

 — into 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...

subtypes.