Tropical rain belt

Rainfall and the tropical climate dominate the tropical rain belt, which oscillates from the northern to the southern tropics over the course of the year, roughly following the solar equator. The tropical rain belt is an area of active rain that is positioned mostly around the tropics. According to the website Journey North, the reason the rain belt is situated near the tropics can be attributed to the fact that most of the sun’s radiation is directed toward the equator, which is located in the middle of the tropics. This solar radiation generates large amounts of heat near the equator providing tropical regions with higher temperatures than most other regions on Earth.

With all this solar radiation, the air around the tropics begins to warm up. Because hot air is less dense than cold air, the hot air rises into the upper levels of the atmosphere and as a result, cold air filters down into the lower levels of the atmosphere. The dynamics that provide the tropics with the rain belt are founded on the principal that warmer air is able to retain more moisture than colder air. When the colder air replaces the warmer air in the lower atmosphere, the abundant moisture from the tropics loses the ability to be stored in the atmosphere. As a result, the excess moisture that cannot be held by the colder air is then turned into thunderstorms and rain showers. These thunderstorms and rain showers are usually located along the equator, but they will extend out to the Tropic of Cancer, which is the 23.5 north latitude, as well as the Tropic of Capricorn, which is the 23.5 south latitude. It is largely a manifestation of the ITCH.

The tropical rain belt lies in the southern hemisphere of the Indian ocean and western Pacific ocean roughly from October to March, and during this time the northern tropics experience a dry season in which precipitation is very rare, and days are typically hot and sunny throughout. From April to September, the rain belt lies in the northern hemisphere, and a wet season occurs there, while the southern tropics experience their dry season.

The rain belt reaches roughly as far north as the Tropic of Cancer and as far south as the Tropic of Capricorn in the western Pacific ocean. Its variation in the Western Hemisphere is minimal, roughly between the equator and the 15th parallel north latitude. Near these latitudes, there is one wet season and one dry season annually. On the equator, there are two wet and two dry seasons as the rain belt passes over twice a year, one moving north and one moving south. Between the tropics and the equator, locations may experience both a short wet and a long wet season. Local geography may substantially modify these climate patterns.

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Wikipedia