The climate within the Earth's surface changes zonal. The most modern classification, which explains the reasons for the formation of a particular type of climate, was developed by B.P. Alisov. It is based on the types of air masses and their movement.
Air masses- These are significant volumes of air with certain properties, the main of which are temperature and moisture content. The properties of air masses are determined by the properties of the surface over which they are formed. Air masses form the troposphere like the lithospheric plates that make up the earth's crust.
Depending on the area of formation, four main types of air masses are distinguished: equatorial, tropical, moderate (polar) and arctic (Antarctic). In addition to the area of formation, the nature of the surface (land or sea), over which air accumulates, also matters. In accordance with this, the main zonal types of air masses are subdivided into sea and continental.
Arctic air masses are formed in high latitudes, above the icy surface of polar countries. Arctic air is characterized by low temperatures and low moisture content.
Moderate air masses clearly divided into marine and continental. Continental temperate air is characterized by low moisture content, high summer and low winter temperatures. Marine temperate air forms over the oceans. It is cool in summer, moderately cold in winter, and constantly humid.
Continental tropical air formed over tropical deserts. It is hot and dry. The sea air is characterized by lower temperatures and much higher humidity.
Equatorial air forming a zone at the equator and over the sea and over land, it has a high temperature and humidity.
Air masses are constantly moving after the sun: in June - to the north, in January - to the south. As a result, territories are formed on the surface of the earth where one type of air masses dominates during the year and where air masses replace each other according to the seasons of the year.
The main sign of the climatic zone is the dominance of certain types of air masses. subdivided into the main(one zonal type of air masses prevails during the year) and transitional(air masses replace each other in seasons). The main climatic zones are designated in accordance with the names of the main zonal types of air masses. For transitional belts, the prefix "sub" is added to the name of the air masses.
Main climatic zones: equatorial, tropical, temperate, arctic (Antarctic); transitional: subequatorial, subtropical, subarctic.
All climatic zones, except for the equatorial, are paired, that is, there are both in the Northern and Southern Hemispheres.
In the equatorial climate zone Equatorial air masses dominate all year round, and low pressure prevails. It is humid and hot all year round. The seasons of the year are not expressed.
Tropical air masses (hot and dry) dominate all year round tropical belts. Due to the downward air movement prevailing throughout the year, there is very little rainfall. Summer temperatures are higher here than in the equatorial zone. The winds are trade winds.
For moderate belts the dominance of moderate air masses throughout the year is characteristic. Western air transport prevails. Temperatures are positive in summer and negative in winter. Due to the prevalence of reduced pressure, a lot of precipitation falls, especially on the oceanic coasts. In winter, precipitation falls in solid form (snow, hail).
In the arctic (antarctic) belt Cold and dry arctic air masses dominate all year round. Characterized by a downward movement of air, north- and southeasterly winds, the prevalence of negative temperatures throughout the year, constant snow cover.
In the subequatorial belt there is a seasonal change in air masses, the seasons of the year are expressed. Summer is hot and humid due to the arrival of equatorial air masses. In winter, tropical air masses dominate, so it is warm, but dry.
In the subtropical zone moderate (in summer) and arctic (in winter) air masses change. Winter is not only harsh but also dry. Summers are much warmer than winters, with a lot of rainfall.
Climatic regions are distinguished within climatic zones with different types of climates - marine, continental, monsoon. Marine type of climate formed under the influence of sea air masses. It is characterized by a small amplitude of air temperature by seasons of the year, high cloudiness, a relatively large amount of precipitation. Continental type of climate formed away from the ocean coast. It is distinguished by a significant annual amplitude of air temperatures, a small amount of precipitation, and a distinct seasons of the year. Monsoon climate characterized by the change of winds according to the seasons of the year. At the same time, with the change of season, the wind changes direction to the opposite, which affects the precipitation regime. Rainy summers give way to dry winters.
The largest number of climatic regions is found within the temperate and subtropical zones of the Northern Hemisphere.
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