A cloudburst is an extreme amount of precipitation in a short period of time, usually accompanied by hail and thunder, which is capable of creating flood conditions. During a cloudburst, more than 20 millimeters (0.79 inches) of rain may fall in a few minutes, and the fall rate is equal to or greater than 100 mm per hour. Cloudbursts can quickly dump large amounts of water, leading to flash floods and landslides.
Cloudbursts are usually local in nature and of brief duration, and most occur in connection with thunderstorms. In these storms, there are violent uprushes of air, which at times prevent the condensing raindrops from falling to the ground. A large amount of water may thus accumulate at high levels, and if the upward currents are weakened, the whole of this water falls at one time. Cloudbursts are especially common in mountainous areas, where the warm air currents of a thunderstorm tend to follow the upward slope of a mountain. The effects of heavy rain are especially striking on mountain slopes because the falling water is concentrated in valleys and gullies, causing sudden and destructive floods.
The term "cloudburst" arose from the notion that clouds were akin to water balloons and could burst, resulting in rapid precipitation. Though this idea has since been disproven, the term remains in use. Cloudbursts can occur when hot water vapor mingles into the cold, resulting in sudden condensation. In India, cloudbursts often occur during the monsoon season, when the southwesterly monsoon winds bring in copious amounts of moisture inland.
Cloudbursts are not defined based on cloud characteristics and do not indicate clouds exploding. They are defined by the amount of rainfall, and according to the India Meteorological Department (IMD), 100 mm of rain in one hour is called a cloudburst. Monitoring stations on the ground can hardly capture the cloudburst characteristics due to their highly localized and short occurrence. Hence, most of these events go unreported due to the lack of monitoring mechanisms in the region, weakening our ability to predict and prepare for them.
