Friday, 25 May, 2012

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 water, or water droplets that persist in liquid form despite subfreezing temperatures due to a [...]

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 and ice crystals. When light beams interact with particles suspended in air, some of the [...]

I saw some cloud pouches hanging down from another cloud. What are they? ENLARGE Mammatus clouds from NOAA 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 [...]

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. The air in contact with the ground can reach high relative humidity if it cools [...]

One fact we know from childhood: every snowflake is unique. Isn’t it? UW-Madison’s snowflake expert, meteorology professor Pao Wang, gently delivered the grim news: “Not really. I think the saying is more or less a picturesque way of saying that there are so many varieties of snowflakes, thousands of different kinds.” Wang studies how snow [...]

Clouds are made of uncountable tiny particles, either water droplets or ice crystals, or a mixture of the two, says Grant Petty, a professor of atmospheric and oceanic sciences at the University of Wisconsin-Madison. “The water droplets are usually about 10-20 micrometers across, or about one-twentieth of the diameter of the period at the end [...]