What causes melting snow?

Answer 1

[ s n o w s t o r m s : t h e c a u s e s ]

Snowstorms generally occur when different types of air masses in the mid-latitudes interact. These storms feed on differences in temperature and moisture. Initially, a wave is typically formed in the mid levels of the atmosphere as a result of a variety of things, be it a mountain range, injection of vorticity (energy), or several other reasons. Assuming certain conditions are in place for this wave to amplify, it will do so and begin to rotate, which effectively moves warm and moist air from one air mass to the north, and much colder and dryer air behind it to the south and east. The boundaries between the air masses constitute the warm and cold fronts of the new cyclone/storm.

Snow storms that produce a lot of snow require an outside source of moisture, such as the Gulf of Mexico or the Atlantic Ocean in the United States. This requires yet more conditions to be just right, namely for the flow (the general wind flow at certain levels of the atmosphere) in the low-mid levels of the atmosphere to be aligned such that moisture can readily be transported from these regions directly into the storm. Another condition that must be met for a healthy storm is the air that is converging and rising in the center of this low pressure system, the snow storm, to have an outlet as it rises up in the atmosphere. In other words, this air must be able to readily diverge at the mid levels of the atmosphere, effectively removing it from the storm and allowing this cycle to continue.

The type of precipitation in a snow storm obviously varies with temperature, but not just at the surface. In a snow storm, all precipitation starts as snow, but it may melt as it falls depending on the temperature profile of the atmosphere. If all levels of the atmosphere are below freezing, precipitation will fall as snow. If it warms below freezing low in the atmosphere, you could get several types of precipitation depending on how deep this layer is - if it is shallow, the snow will melt but refreeze into sleet. If it is deep, it will melt and not get a chance to refreeze, falling as rain. If the temperature at the surface is still below freezing however, the rain will freeze on the surfaces as freezing rain.

So snow storms generally need a source of moisture, an injection of energy at the mid levels of the atmosphere, and some mechanism that serves as a catalyst.

Answer 2

Snow is caused by water droplets being blown around up in the clouds and freezing into crystals. These then fall, just as the rain eventually would have, as snow. On average, snow takes up about 9 times as much space as rain, so what would have been an inch of rain can become nine inches of snow.

Answer 3

A snowfall occurs when the clouds get really cold, and form ice crystals in the air. It can be as warm as 40 degrees Fahrenheit on the ground, yet be 0 degrees Fahrenheit in the clouds, which therefore would cause snow to occur

Answer 4

Snow is caused when rain falls in conditions below freezing.

Answer 5

Snow occurs when it is around 0 degrees celsius and it 'rains' the droplets freeze up and turn into snow.

Answer 6

the hot sun