TUESDAY FEBRUARY 13 - SENSITIVITY OF DOPPLER TO SNOW INTENSITY


When you think about the many ways that Doppler Radar has revolutionized meteorology, right at the top of the list is better detection of potential tornado-producing thunderstorms. But Doppler Radar has been a revolution in other ways too, one of which gets a lot of use this time of year. That's the ability to tell the difference between various intensities of snow, something older radars couldn't do very well, if at all.

Radar works by sending out pulses of radiation. When that radiation strikes raindrops or snowflakes, some of it is reflected back to a receiver. In general, the more radiation that comes back, the heavier the rain or snow. Snow is harder to detect with radar than rain because snowflakes actually have a lot of holes in them. So it's easier for the radar beam to go right through a snowflake without reflecting back.

But Doppler radar is extremely sensitive, even to relatively small amounts of reflected radiation. So it can actually differentiate bands of heavier snow within larger areas of lighter snow. And this can help meteorologists tell you with more detail where the heaviest snow is falling in a storm.

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