Thunderstorm

Thunderstorm

Typically, the swirl of stormy weather obscures the cells at the heart of severe thunderstorms. This uncommonly clear view of an entire thunderstorm cell, with the top of the growing cumulonimbus tower topping out at 40,000 feet, reveals many interesting features, including “fall streaks” of what may be hail from the underside of the overhanging anvil portion of the cloud. Shortly after this photo was taken on May 22, 2011, near Madison, the storm pelted the Sun Prairie area with large, damaging hail. More »

Hole-punch clouds

Hole-punch clouds

Mysterious holes in clouds, such as this one, have long fascinated the public and, until recently, baffled scientists. New research shows that turboprop or jet aircraft punch these holes, causing narrow bands of rain or snowfall. Clouds often contain supercooled… More »

Why are clouds white?

Why are clouds white?

Why are clouds white? Photograph of Cumulus clouds in fair weather taken by Michael Jastremsk Clouds are made of water and clean water is clear. So why are clouds white? Because clouds are made of billions of small water droplets… More »

I saw some cloud pouches hanging down from another cloud. What are they?

I saw some cloud pouches hanging down from another cloud. What are they?

Those are mammatus clouds, which are often, though not always, associated with thunderstorms. Mammatus often extend from the bottom of the anvil cloud of a thunderstorm, also called a cumulonimbus cloud, and indicate an intense storm is near-by. Mammatus clouds may have a very ominous appearance; however, they are usually seen after the worst weather has passed.
More »

How does fog form?

How does fog form?

How does fog form? Photo: NASA Fog is a cloud in contact with the ground. When the relative humidity approaches 100 percent, water vapor condenses on tiny particles suspended in the air to form a suspension of small water drops.… More »