This winter storm brought fluffy snow in some places, but wet snow in others. Why?
Forecasters said the snow that fell in the Mid-Atlantic Tuesday was dry and fluffy to the north of Washington, D.C., but heavier and wetter to the south.
Why is this? Air temperature is the primary factor in determining the kind of snow that falls. While powdery snow is loved by skiers, wet snow is hard to shovel (but great for making snowmen).
Wet snow occurs when the air temperature near the surface is above freezing, causing the snowflakes to partially melt before reaching the surface, CompuWeather said in an online report. "This causes the snowflakes to become sticky and easily adhere to and accumulate on nearly all outdoor surfaces," CompuWeather meteorologist Eric DeRoche said.
Weather.com meteorologist Chris Dolce said that wet, heavy snowfall accumulations are commonly found in early and late-season storms, and often in the South. "That type of snow is difficult to shovel and can be more likely to bring down trees and power lines," he said.
Dry snow is more common
Dry snow is more common as it occurs when the surface air temperature is below freezing. "Unlike wet snow, dry snow is powdery and cannot easily be formed into snowballs or snowmen," DeRoche said. "In addition, colder air temperatures correlate to lighter and fluffier snow that contains less water per inch."
This snowfall is typically dry and fluffier and is often prone to blowing around in the wind, Dolce said.
How much does snow weigh?
The weight of snow can vary dramatically: A cubic foot of dry, powdery snow might weigh as little as three pounds, while a cubic foot of heavy, wet snow can weigh as much as 10 pounds. (A cubic foot measures one foot, by one foot, by one foot).
In addition, "you may have heard that melting 10 inches of snow gives you an inch of water," Dolce said. "While that is valid at times, how much snow comes from an 'inch of water' has many more factors that can significantly alter the resulting snowfall."
Those factors include the depth of the warm layer from the surface into the snow-producing cloud as well as the amount of ice in the snow-producing cloud, the National Weather Service said.
Also, if its windy, snowflakes can fracture, losing their "lacy" structure and leading to lower accumulations (lower snow ratios). And deep cold, in general, promotes higher snow ratios.