(Many modern weather radar systems are Doppler radars.) So, how does a Doppler radar work?Ī Doppler radar adds to the capabilities of traditional weather radar systems by possessing the ability to measure the direction and velocity of wind, and as a result, the direction the weather is moving in.
The Doppler radar system is one such case. This is one of the main reasons why weather radars are located in large open areas.Īdvances in radar technology have allowed us to add to the functionality of the conventional radar. Radar beams cannot "see'' through and are obstructed by permanent fixtures such as tall buildings and mountains.Sometimes a radar can "falsely" pick up what is perceived to be precipitation, which is in reality flocks of birds, smoke, or swarms of insects.This falls within what is known as the "cone of silence." A weather radar cannot detect echoes that are very close to or above the radar itself.It is difficult to pick up drizzle that is close to the ground, as it often falls below the radar's beam, and the droplets are sometimes too small to detect (difficult to bounce back the signal).This does, however, not reflect the conditions on the surface, which can give a false reading as a result. As a result of the previous point, the radar may be able to pick up precipitation that is much higher up in the air beyond its optical limit.The radar beam travels in a straight line, meaning beyond its maximum range, it is unable to detect objects close to the surface of the ground. This is mainly due to the curvature of the earth. The optical range of a weather radar is limited to 5 - 200 kilometers (3 -124 miles).Here are a few of the most notable drawbacks: With all the advantages and benefits of the weather radar, they are not without their shortcomings or limitations. This helps anyone viewing the picture to know when the image was created, no matter where in the world or in which timezone they are. The two terms are often used interchangeably, which can be confusing.īe sure to read the weather scale that accompanies every radar image to confirm what each color means for that specific image.Įach radar image has a timestamp at the bottom of the image, which is in Universal (Greenwich) Time or UTC. (In many cases, black represents hail.)Ĭolor scales are also used to indicate the amount of rainfall, not just the intensity. Usually, the most intense form of precipitation is indicated by black. On modern-day weather systems, the results captured by a weather radar are displayed as a color image on a display screen.Ī color scale is used to show the intensity of the precipitation. The resulting animated radar image forms a thirty-minute loop.Īlthough a radar image does not give you a clear and definite forecast, it shows you where the rainfall has been, as well the direction in which it may be moving. The strength of the echo, on the other hand, provides a strong suggestion of the type of precipitation encountered (rain, hail, or snow).Īlthough this varies from one radar to another, a signal is normally sent out with a frequency of around once every six to ten minutes. The length of time it takes the echo to return to the sender indicates how far away the precipitation is from the radar. The radar can determine a lot from the characteristics of the reflected wave. If the signal encounters any precipitation (rain, hail, or snow), it is reflected back to the radar tower, which interprets the reflected signal (also called the echo).
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