METEOROLOGIST JEFF HABY
Snow forms in clouds that are below freezing. Much of the rain that makes it to the surface
started out as snow high aloft and then melted before reaching the ground. When saturated
air rises it condenses. In other words the moisture turns from a gas and into a liquid. When
saturated air cools the moisture condenses out similar to the way in which you will
see moisture develop on the outside of a glass of ice-water. When it is below freezing the
vapor turns into ice. Due to the nature of the water molecule the ice will develop into
6 sided crystals. If you look at a snowflake you will notice it is likely a bunch of 6 sided
ice crystals joined together. When a snowflake gets big enough in a cloud then gravity will
push it down toward the surface. The snowflake will continue to get bigger as it joins
with other falling crystals. This is especially true if the snowflake is sticky. By sticky that
means the snowflake has some liquid water coating on it. The biggest snowflakes tend to
occur when the temperature is near freezing. When it is very cold (well below freezing) the snowflakes
tend to be smaller and they do not stick together as well.
To get snow the temperatures need to be cold enough to allow the snowflake to fall to the surface
without melting. There also needs to be clouds that build up enough to develop the snow. Many snow
events occur due to either rising moisture on the cold side of a low pressure system, upslope
rising air that produces snow, and snow to the north of a warm front. Snow is so beautiful
to watch. I look forward to each time it snows.
|
|
|