Speaker 1: Welcome to Brainstuff from house stuff works dot com where
Speaker 1: smart happens. Hi Am Marshall Brain with today's question, if
Speaker 1: the temperature is thirty degrees fahrenheit outside, why do we
Speaker 1: sometimes get snow and other times we get freezing rain.
Speaker 1: When you watch the local weather report on the evening news,
Speaker 1: you always hear the current temperature. It may be, for example,
Speaker 1: thirty two degrees fahrenheit or zero degrees celsius outside. That's
Speaker 1: useful information, but if it's precipitating, it is only one
Speaker 1: part of the puzzle. It turns out that the atmosphere
Speaker 1: is layered, and these layers control the form that precipitation
Speaker 1: will take on the ground. The local weather report only
Speaker 1: gives us the ground level temperature. In order to understand sleet, snow,
Speaker 1: and freezing rain. What we need to know is perhaps
Speaker 1: four to six different temperature readings at different altitudes. Precipitation
Speaker 1: starts in the cloud as snow. As it falls, it
Speaker 1: may travel through a layer of air that has a
Speaker 1: temperature greater than thirty two degrees fahrenheit. This layer melts
Speaker 1: the snow into rain. If the temperature at ground level
Speaker 1: is below freezing, then the water may refreeze in the
Speaker 1: air and then we get sleep. Or if the layer
Speaker 1: of subfreezing air at ground level is thin, the precipitation
Speaker 1: falls as rain, but then it freezes once it touches
Speaker 1: the freezing object on the ground. For snow to fall,
Speaker 1: all the layers of air that the snow falls through
Speaker 1: once it leaves the cloud must be sub freezing. The
Speaker 1: warm middle layers are normally caused by the movement of
Speaker 1: warm fronts or cold fronts through the area. In the southeast,
Speaker 1: temperatures often hover around thirty two degrees Fahrenheits, so the
Speaker 1: form of precipitation can change all the time. In more
Speaker 1: northern areas, the temperature is well below freezing in all
Speaker 1: the layers, so snow is a sure thing. You have
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