Atmosphere And Weather

How does Snow Form



Tweet
Carolyn Tytler's image for:
"How does Snow Form"
Caption: 
Location: 
Image by: 
©  

"Snowflakes are kisses from heaven."   Author unknown.

Snow flakes don't exactly originate in heaven, but they do form high up in the atmosphere, where it is very cold. If the temperature is 32 degrees F. (0 degrees C.) or lower, tiny drops of water vapor freeze and become ice crystals.

Sometimes an ice crystal will cling to a dust particle, a speck of volcanic ash or a grain of sea salt in the atmosphere, and these will become the nucleus of  a snowflake,

When the air is humid, millions of ice crystals form in one area and these result in the formation of a cloud. Inside the cloud, the tiny crystals swirl up, down and around, collide with others and cling together. As they grow larger, they form the delicate patterns of snowflakes. Many are symmetrical and have six sides.

When the flakes are heavy enough, they fall from the cloud. What happens next depends on the temperature and humidity of the air between the cloud and the earth.

If the air is warm and humid, the flakes melt and fall as rain.

When the air is cold but dry, the flakes remain small, and fall to earth. If the ground is also cold, they will remain frozen and gradually cover the earth with a beautiful, white blanket of snow.

If the temperature of the earth is above freezing, the snowflakes will melt as they land, and be absorbed into the ground.

If the air is cold but humid, the flakes will pick up more water vapor on the way down, and form six evenly spaced branches, which in turn collect even more water vapor to form large fluffy hexagons of snow, no two alike.  

If the temperature is not too cold, and the air extremely humid,  a snowflake can grow to be as large as 1 or 2 centimeters (0.393 to 0. 787 of an inch) across! 

Sometimes, between the cloud and the earth, the temperature may change several times . The crystals can melt and refreeze. If they melt, then refreeze as they approach the earth, they will fall to the ground as hail.

In a mountainous region, it is possible to see snow falling on the cold, distant mountaintop, while raindrops fall on the village folk in the warmer valley below.

Snowflakes may not be kisses from heaven, but they are wondrous in their diversity of  size and pattern while still maintaining their characteristic hexagonal shape.

Jeanette Winterson, the British novelist reflected: "They say that every snowflake is different. If that were true, how could the world go on? How could we ever get up off our knees? How could we ever recover from the wonder of it? "

How indeed.

Tweet
More about this author: Carolyn Tytler

From Around the Web




ARTICLE SOURCES AND CITATIONS