The central belt of the planet got its name equatorial due to its location on both sides of the equator from 5-8 degrees north to 4-11 degrees south latitude.
Eternal Summer
Limited by subequatorial belts, the equatorial belt consists of three regions:
- South America Continent: Amazon River Lowlands;
- Mainland Africa: equatorial part; Gulf of Guinea;
- Part of the Greater Sunda Islands and the nearest water area.
Equatorial latitudes simultaneously cover areas of both parts of the world, with the same climatic conditions in both the Northern and Southern hemispheres.
Formation of equatorial air masses
The amount of heat that the sun gives off the earth's surface is one of the main factors affecting the climate of any corner of the Earth. The degree of heating of the surface of the planet depends on the angle at which the sun's rays fall on it. The closer to the equator, the more the surface of the Earth warms up, therefore, the temperature of the ground air increases.
On the territory of the equatorial zone, the angle of incidence of the Sun's rays is the highest, so the average annual air temperature in the regions of the equatorial zone is +26 degrees with slight differences. The air masses of the equatorial belt, heating up, rise and create an upward movement of air currents.
A zone of low atmospheric pressure is formed near the surface of the Earth - the equatorial depression. The heated and humid air rising up becomes saturated and cools there. As a result of thermal conversion, a lot of cumulus clouds accumulate and fall as rain.
The air masses of the equatorial belt that form in the depression zone always have a high temperature. Humidity in this area is also increased.
This is what makes the equatorial climate zone unique. The characteristics of air masses are always similar. Since they form in a zone of low atmospheric pressure over land and oceans, scientists do not classify them into marine and continental climate subtypes.
Features of air masses
The prevailing air masses of the equatorial belt form the equatorial type of climate, which is characterized by:
- High constant air temperature from 24 0С to 28 0С with slight fluctuations during the year with a difference of 2-30S. The change of seasons passes unnoticed, summer dominates all year round. The average temperature in the equatorial zone does not change throughout the year.
- Precipitation abundance with two peaksprecipitation corresponding to the zenith position of the Sun, and two minima during the solstices. It's raining, but unevenly.
- Precipitation in the equatorial zone and the amount of precipitation per year differs for different regions of the equatorial zone.
Typical equatorial climate is characteristic of the Western Amazon and the Congo Basin. In the Congo Basin, the amount of precipitation per year is 1200-1500 mm, in some places 2000 mm per year. The area of the Amazonian lowland is much larger than the Congo Basin, the air masses of the equatorial belt are formed more intensively. The annual amount of precipitation reaches 2000-3000 mm. This is many times the annual rate.
Equatorial climate zone: climate characteristics
The western part of the Andes and the north of the Guinean coast are characterized by the most abundant precipitation, their amount can exceed 5000 mm per year, in some places up to 10000 mm per year. Such an abundance of precipitation is influenced by a strong countercurrent between the trade winds of the north and south. In these areas, the summer maximum precipitation is expressed.
Precipitation regime in the equatorial zone varies significantly by season. The dry period is either absent or lasts one to two months. The large difference in precipitation between summer and winter in these regions is due to the dry and dusty West African trade wind Harmattan. From late November to early March, it blows from the Sahara towards the Gulf of Guinea.
Equatorial belt: winds that shape the climate
The abundance of precipitation is directly related to the intratropical trade wind convergence zone, a zone where air currents converge. The convergence zone stretches along the equator, coincides with the zone of low atmospheric pressure, and is located north of the equator for most of the year. Seasonally, the ongoing shifts in the convergence zone are accompanied by changes that are most noticeable in the Indian Ocean basin.
Here the trade winds turn into monsoons. Steady winds, depending on the season, change their direction. The strength of the wind can change: from weak to squall. Most of all tropical cyclones form in this zone. Tropical latitudes are characterized by high atmospheric pressure.
Trade winds and monsoons
They form air streams that rush to the low pressure zone - to the equator. Due to the rotation of the Earth, the northeast trade wind near the equator takes a northerly direction, and the southeast trade wind takes a southerly direction. When they meet, they form a calm - a windless strip. Trade winds are weak air currents that blow along the equator all year round and are the most stable winds on the planet.
Thus, after the days of the equinox, the maximum precipitation falls in the equatorial zone. A slight decrease in precipitation is observed after the days of the solstices. Above the earth's surface, heated by the sun's rays, a cluster of clouds forms. It usually rains in the afternoon, accompanied by thunderstorms. Over the sea, showers and thunderstorms occur at night, this is the difference between the maritime and continental climates.
There is so much precipitation that the moisture does not have time to evaporate. The relative humidity is kept at 80-95%. Excess moisture swamps the soil, contributing to the growth of impenetrable multi-tiered equatorial forests. Western monsoons constantly blow over the humid forests of equatorial latitudes in summer, and eastern monsoons in winter, in Africa the Guinean monsoon and Indonesian monsoons.
