WEBVTT - Why do freezing temperatures yield both snow and rain?

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<v Speaker 1>Welcome to Brainstuff from house stuff works dot com where

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<v Speaker 1>smart happens. Hi Am Marshall Brain with today's question, if

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<v Speaker 1>the temperature is thirty degrees fahrenheit outside, why do we

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<v Speaker 1>sometimes get snow and other times we get freezing rain.

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<v Speaker 1>When you watch the local weather report on the evening news,

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<v Speaker 1>you always hear the current temperature. It may be, for example,

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<v Speaker 1>thirty two degrees fahrenheit or zero degrees celsius outside. That's

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<v Speaker 1>useful information, but if it's precipitating, it is only one

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<v Speaker 1>part of the puzzle. It turns out that the atmosphere

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<v Speaker 1>is layered, and these layers control the form that precipitation

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<v Speaker 1>will take on the ground. The local weather report only

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<v Speaker 1>gives us the ground level temperature. In order to understand sleet, snow,

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<v Speaker 1>and freezing rain. What we need to know is perhaps

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<v Speaker 1>four to six different temperature readings at different altitudes. Precipitation

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<v Speaker 1>starts in the cloud as snow. As it falls, it

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<v Speaker 1>may travel through a layer of air that has a

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<v Speaker 1>temperature greater than thirty two degrees fahrenheit. This layer melts

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<v Speaker 1>the snow into rain. If the temperature at ground level

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<v Speaker 1>is below freezing, then the water may refreeze in the

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<v Speaker 1>air and then we get sleep. Or if the layer

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<v Speaker 1>of subfreezing air at ground level is thin, the precipitation

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<v Speaker 1>falls as rain, but then it freezes once it touches

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<v Speaker 1>the freezing object on the ground. For snow to fall,

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<v Speaker 1>all the layers of air that the snow falls through

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<v Speaker 1>once it leaves the cloud must be sub freezing. The

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<v Speaker 1>warm middle layers are normally caused by the movement of

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<v Speaker 1>warm fronts or cold fronts through the area. In the southeast,

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<v Speaker 1>temperatures often hover around thirty two degrees Fahrenheits, so the

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<v Speaker 1>form of precipitation can change all the time. In more

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<v Speaker 1>northern areas, the temperature is well below freezing in all

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<v Speaker 1>the layers, so snow is a sure thing. You have

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<v Speaker 1>any ideas or suggestions for this podcast, If so, please

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<v Speaker 1>send me an email at podcast at how stuff works

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