Convectional rainfall is the most common type of rainfall in equatorial regions. This type of rainfall occurs due to the intense heating of the Earth's surface, which leads to the formation of cumulonimbus clouds and subsequent precipitation.

The process of convectional rainfall can be explained in the following steps:

1. Heating of the Earth's Surface: In equatorial regions, the sun's rays are almost perpendicular to the Earth's surface, resulting in intense heating. This heating causes the air near the surface to warm up and become less dense.

2. Upward Movement of Warm Air: As the warm air near the surface becomes less dense, it starts to rise. This upward movement is known as convection. The warm air carries moisture from the surface, forming updrafts.

3. Condensation and Cloud Formation: As the warm air rises, it expands and cools. As it cools, the moisture it carries condenses into water droplets, forming cumulus clouds. These clouds can reach great heights due to the strong updrafts.

4. Precipitation: Within the cumulus clouds, the water droplets continue to grow by colliding and merging with each other. Eventually, the droplets become too heavy to be supported by the updrafts and fall to the ground as rainfall. This precipitation can be in the form of showers or thunderstorms, depending on the intensity of the convection.

Convectional rainfall is most common in equatorial regions due to the high temperatures and abundant moisture present in these areas. The constant heating of the surface and the resulting convection processes lead to the formation of cumulonimbus clouds and frequent episodes of rainfall.

This type of rainfall is often characterized by intense and short-duration showers, which can result in high rainfall totals. It plays a crucial role in maintaining the lush and diverse ecosystems found in equatorial regions, as it provides water for vegetation and supports various forms of life.

Overall, convectional rainfall is the dominant type of rainfall in equatorial regions due to the unique climatic conditions found in these areas.