Embedded Files
Odd as it may sound, clear air can also produce radar echo. The echo may be caused by concentrations of haze or dust particles, insects, or even small-scale variations in air density such as might occur on a warm sunny day. The structures of these clear air echoes are often quite useful for weather forecasting.
Frequently, the clear air echo takes the form of a thin line. This line usually represents a convergence line, and often features density variations as well. Cold fronts and outflow boundaries often produce thin line echoes. So even if there's no precipitation, it is often possible to determine the exact location of the cold front using weather radar.
Other times, the clear air echo may take the form of many parallel lines. These lines, if they are oriented parallel to the surface wind direction, are produced by the ground heating the air from below and producing overturning rolls of air. If the air is moist, long rows of shallow convective clouds can be found along the top of each parallel line of echo. So if these features are present, you can infer the wind pattern in the vicinity of the radar.
Report abuse