Tropical monsoon climate

A tropical monsoon climate is a specific subtype of tropical weather. In the Köppen climate classification system, it is known as the Am category. This climate is defined by having high monthly mean temperatures every month of the year. It also features a distinct dry season. This climate sits as an intermediate zone between two other major types. One type is the tropical rainforest climate, which is very wet. The other is the tropical savanna climate, which is much drier.

The mechanism behind this climate is the monsoon circulation. A monsoon is a seasonal change in wind direction. This change happens because land and water heat up at different rates. In Asia, the wind direction shifts with the seasons. During the high-sun or summer season, there is an onshore flow. This means air moves from the ocean toward the land. This moist air brings significant rainfall. In the low-sun or winter season, there is an offshore flow. This occurs when air moves from the land toward the water.

In other parts of the world, different factors control the rain. In Africa, changing pressure patterns affect the seasonality of precipitation. During the high-sun season, the Intertropical convergence zone, or ITCZ, induces rain. The ITCZ is a region where air rises and creates clouds. During the low-sun season, the subtropical high creates dry conditions. Monsoon climates in Africa and the Americas often sit along trade wind coasts. These winds help shape the seasonal patterns of the region.

There are generally two distinct varieties of the tropical monsoon climate. The first variety has less pronounced dry seasons. These regions receive copious amounts of rain during the wet seasons. This rain often comes in the form of frequent thunderstorms. Unlike most tropical savannas, these areas still get a sizeable amount of precipitation during the dry season. However, they do not receive enough rain to be classified as a tropical rainforest. This version is essentially a middle ground between the wet and dry extremes.

The second variety features extraordinary rainy wet seasons and pronounced dry seasons. These dry seasons are similar in length to those in a tropical savanna. This is followed by a sustained period of extreme rainfall. In some instances, precipitation can exceed 1,000 mm in a single month. This high level of rain can last for two or more consecutive months. Most tropical savanna climates do not experience this level of sustained, heavy rainfall.

We can identify these climates by looking at specific precipitation numbers. In a tropical monsoon climate, the driest month averages less than 60 mm of rain. However, it must still receive more than 60 mm of total annual precipitation to stay in this category. This distinguishes it from the tropical savanna climate. In a savanna climate, the driest month has less than 60 mm of precipitation. Additionally, that amount is also less than 60% of the average monthly precipitation.

Tropical monsoon climates appear in many different parts of the globe. They are most common in West and Central Africa and in Asia. You can find them throughout South and Southeast Asia as well. They also exist in northern South America and Central America. Other locations include sections of the Caribbean and North America, specifically South Florida. Northern Australia also contains these zones.

Many major cities are located within these monsoon zones. In Asia, cities include Manila and Quezon City in the Philippines. Jakarta and Makassar are located in Indonesia. In India, Kochi and Thiruvananthapuram are in Kerala. In Africa, Douala is in Cameroon and Monrovia is in Liberia. In the Americas, Recife is in Brazil and Panama City is in Panama. These locations all experience the unique balance of heat and seasonal wind shifts.