The Important Difference Between Wet Snow and Dry Snow
by Eric DeRoche, CompuWeather Meteorologist
Snow forms when water vapor in the atmosphere freezes directly into ice crystals and falls to the ground as precipitation. When it falls heavily or for long periods, it can accumulate to several inches and become a travel hazard on roads and walkways. This is common knowledge to people who experience cold winter seasons. However, there are different types of snow that have varying impacts that may not be common knowledge to all. One such difference is wet snow vs. dry snow. The consistency of the snow makes a big difference when it comes to the snow’s effects.
Wet snow occurs when the air temperature near the surface is above freezing, causing the snowflakes to partially melt before reaching the surface. This causes the snowflakes to become sticky and easily adhere to and accumulate on nearly all outdoor surfaces.
A few inches of wet snow accumulation can make for beautiful winter landscapes, coating everything from tree limbs to fence rails. The stickiness of wet snow also makes it easy to form into snowballs and snowmen. But while wet snow can be fun for the family and make for great photo opportunities, it can cause a lot of problems when several inches of it accumulates. Wet snow not only sticks to everything, but it is also heavier than dry snow. One inch of wet snow can contain 2 to 3 times more water than one inch of dry snow, making it that much heavier. This makes it difficult to shovel and the weight of the wet snow can snap tree limbs and power lines causing power outages. In extreme cases, structural damage and roof collapses can occur. On October 29, 2011, a major autumn snow storm brought over a foot of heavy wet snow to many parts of the northeastern U.S., causing widespread tree damage and power outages affecting over 2 million people. More recently, on December 5-6, 2020, a heavy wet snow event combined with strong winds caused widespread damage to trees and power outages affecting over 200,000 people across parts of Maine and New Hampshire.
Dry snow is more common as it occurs when the surface air temperature is below freezing. Without the stickiness of wet snow, dry snow tends to accumulate only on the ground and other level surfaces with little or no accumulation on trees or power lines.
Unlike wet snow, dry snow is powdery and cannot easily be formed into snowballs or snowmen. In addition, colder air temperatures correlate to lighter and fluffier snow that contains less water per inch. This makes it easier to shovel, but also makes it more susceptible to significant blowing and drifting when accompanied by strong winds making it more difficult to keep roads and walkways cleared.
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