Clear Air Echoes
Generally occur close to the radar (eg within 80 km).
Targets can be fluctuations in the refractive index, insects and birds, etc. They are more of a summer phenomenon though they can appear in winter. Can be used to delineated gust fronts, sea breeze fronts, outflow boundaries, prevailing winds, etc.
•
•
•
•Birds and Insects
Swarms of insects and flocks of birds have been observed
on radar and weather radar has been used in studies of migration.
Echoes are distinctive and can sometimes be confirmed visually or are
consistent with known habits. Since, on average, insects are advected
along with the mean winds, they provide "tracers" to diagnose low-level
winds, and can allow tracking of such phenomena as gust fronts and the
sea breeze front. The threshold of detection must be set fairly low for
these purposes.
Chaff
•
•
•
Sunrise/Sunset
Interference due to radio emissions from the sun may be
seen near sunrise and sunset. This appears as a radial line from the
radar in the direction of the sun.
