The above weather radar map displays a National Weather Service enhanced radar image from the Atlanta, Georgia radar site. The Atlanta weather radar map updates approximately every ten minutes when in clear air mode. In precipitation mode radar updates occur more often, possibly five to six minutes apart. Atlanta's weather radar is most sensitive in the clear air mode. As the clear air mode has a slower antenna rotation rate. Allowing the radar to sample a given volume of Atlanta's atmosphere longer. Increased sampling increases the weather radar's ability to detect smaller objects in the atmosphere. Much of what can be seen on radar in clear air mode is airborne dust and particulate matter in the Atanta area.
When precipitation occurs the radar does not need to be as sensitive. As the radar is able to return more signals because of the precipitation in the atmosphere. By switching the radar antenna to a faster rotation speed Atlanta's weather radar images update more often. Allowing Atlanta's weather meteorologists to better track storm movements that might threaten the Atanta, Georgia area.
The DBZ color code chart on the bottom right of the above Atlanta weather radar image relates to rainfall intensity. Rainfall normally occurs when the DBZ intensity reaches a level of 20 or higher. A DBZ intensity of 15 or below is generally just an indication of interference being shown by the radar. The higher the DBZ level of intensity shown on the weather radar map the harder the rainfall.
