when Big winter storms When you move in, they can bring bad weather ranging from snow to sleet and sleet — or maybe Extreme cold and dangerous.
Here’s a look at some of the weather conditions and how they differ from one place to another.
For snow to stick, it needs cold, steady air all the way from where the flakes form in the clouds to the ground. If the temperature is below freezing all the way, the snowflakes never melt, so nothing turns into ice.
“The further north we go, the deeper the Arctic layer, the more likely it is to support snow,” said Judah Cohen, a research scientist at the Massachusetts Institute of Technology.
Farther south, the atmosphere may sandwich warm air between cold layers. This is how sleet and freezing rain occurs.
“Snowflakes form, they fall and then they meet a warm layer, a layer above freezing, and they will melt,” Cohen said. “But then there is another layer near the surface that is below freezing again, so it will freeze again before it reaches the ground.”
Frost requires the substrate to be cold enough so that raindrops freeze again when they hit the ground, creating bouncy ice globules. If that cold bottom layer is shallow, the rain won’t have enough time to freeze in the air. So they hit the ground as raindrops and freeze on contact.
Then there is the sifter, a rare combination of snow and sleet. Not quite soft, not quite hard.
“It’s snow that tried to melt on its way down, but it didn’t quite melt,” said David Robinson, a New Jersey state climatologist at Rutgers University. “It came out of this six-point crystalline shape and started looking more like a cotton ball. So it didn’t get to the point of complete melting where it could freeze again as icy frost.”
There’s also hail, which Robinson said some people mistakenly use to describe frost. But real hail may not occur in a winter storm. This usually occurs in the summer because it requires warmer air closer to the surface. This creates an updraft that allows the rain to move up, freeze, fall, and move up again, forming layers of ice that resemble the layers of an onion.
Snow can be dangerous, enough to send cars sliding into ditches and threaten lives in power outage conditions. But at least it can be plowed.
The ice in the frost makes movement more difficult.
But the most damaging moisture is freezing rain, Cohen said, because it turns roads into skating rinks and can be so heavy that it has the potential to topple. Power lines.
Then there is the extreme cold.
When the National Weather Service sees that the expected temperatures are… Wind chill Low enough to be dangerous, they issue alerts.
A cold weather warning means hazardous weather is possible. A very cold watch means the weather is life-threatening. An extreme cold warning means the weather is likely life-threatening.
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