A single cumulonimbus storm cloud can grow nearly twice as tall as Mount Everest.

Cumulonimbus clouds are the only cloud types that span all three cloud altitude layers. While the base of these clouds may sit just 500 meters above the ground, their tops can reach the tropopause, which is the boundary between the troposphere and the stratosphere. In tropical regions, this boundary is much higher than at the poles, allowing storm cells to reach staggering altitudes of up to 18,000 meters.The growth of these clouds is driven by atmospheric instability and convection. As warm, moist air rises rapidly, it cools and condenses, releasing latent heat that further fuels the upward momentum. This process creates powerful updrafts that can exceed speeds of 160 kilometers per hour. When the rising air hits the stable air of the stratosphere, it can no longer rise vertically and instead spreads out horizontally, forming the characteristic 'anvil' top.According to the World Meteorological Organization, these clouds are the primary drivers of extreme weather events. The immense vertical distance within the cloud allows for the separation of electrical charges, which leads to lightning. It also provides enough room for water droplets to freeze and circulate multiple times, growing into large hailstones before finally falling to Earth. By comparison, Mount Everest stands at 8,848 meters, meaning a large tropical cumulonimbus can be more than twice the height of the world's tallest mountain.