![]() ![]() Meteorologists can observe rapidly developing storms or collapsing storms using this scanning method. These different elevation angles allow meteorologists to interrogate storms at different heights above the ground as opposed to just one. In an effort to scan as much of the atmosphere as possible as quickly as possible, the WSR-88D employs a scanning strategy in which the antenna will raise through as many as 15 predefined elevation angles. The rest of the time, 59 minutes and 53 seconds, is spent listening for returns. For every hour, the radar spends a little more than 7 seconds actually transmitting pulses. The extremely short time that the transmitter is actually on means that the radar spends the vast majority of its time listening for returns. In between each transmitted pulse, the radar listens for returns. Each transmitted pulse only lasts 1.57 millionths of a second (0.00000157) and is repeated around 1300 times per second. The majority of the time, the radar will operate in short pulse mode. The radar has two operating modes: short pulse and long pulse. Radar pulses are transmitted away from the radar at the speed of light, but they are very short in duration. As the vehicle passes your location, the siren or whistle's pitch lowers. You may have heard this effect from an emergency vehicle or train. As an object moves away from your location, sound waves are stretched, resulting in a lower frequency. The phase shift is similar to the "Doppler shift" observed with sound waves – sound from an object moving toward your location is higher pitch due to compression (a change in the phase) of sound waves. This phase shift is used to determine the velocity of the target. When the pulse hits a moving target, the phase of the returned wave is “shifted” or changed. When the radar transmits a pulse, it keeps track of the phase and amplitude (shape, position, and form) of that pulse. In addition to range information, the WSR-88D is a Doppler radar, meaning that it can determine velocity of a target. By calculating the amount of time it takes for a pulse to be transmitted, strike a target, and return to the radar antenna, the system can determine the range (or distance) of the target from the radar. This means that the transmitter sends out very brief pulses of radio waves rather than a continuous stream of waves. National Centers for Environmental Prediction.Preparedness and Mitigation: Individuals (You!).Preparedness and Mitigation: Communities.The Positive and Negative Side of Lightning.Please consult your device documentation for instructions. On mobile devices, you can save the bookmark as an easy-access icon similar to other apps. For example, if you select "Weather for a location," then select a location, the bookmark will return to your location on your next visit. You may bookmark the URL to return later to the same view with the selected settings. The URL will automatically update as you select the view and settings. This view is similar to a radar application on a phone that provides radar, current weather, alerts and the forecast for a location. This view combines radar station products into a single layer called a mosaic and storm based alerts. This view provides specific radar products for a selected radar station and storm based alerts. This site is organized into views that provide relevant radar products and weather information for a common task or goal.
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