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WHAT IS BRIGHT BANDING
AND HOW DOES IT OCCUR?

METEOROLOGIST JEFF HABY

Bright banding occurs due to the higher reflectivities associated with snow that is melting as it is falling aloft. Ice is a better absorber of radar radiation compared to liquid water. Because of this, snow will show a lower reflectivity on radar when it has the same moisture content as a rain event. When the snow is melting however, a film of water forms on the outside of the snowflake. Since snowflakes can be fairly large, when there is a film of water on the snowflake it has the same reflectivity as a a giant raindrop or small wet hail.

A radar beam will generally sample a higher elevation as it moves away from the radar site. Because the melting of the snowflakes occurs within a specific elevation range aloft, there will be a higher reflectivity as the radar beam moves through this layer. This can produce a circular or arcing band of higher reflectivity around the radar site on the reflectivity display.

Below are some bright banding examples (more examples will be added over time):

Dallas / Ft. Worth Area Bright Band