The Doppler radar uses what is known as the Doppler effect. This is also known as “the gap.” The Doppler Effect The curvature of the earth results in the radar signals being higher off the ground when the weather disk is farther away. This permits forecasters to determine both the size and shape of precipitation, which is useful when differentiating snow from rain.Īs with all radars, dual-polarization technology is less relevant the farther the radar site is from the signals returning to it. This type of weather radar allows for two beams to be sent out with vertical and horizontal orientations. However, this radar not only measures the motion of the precipitation but also the distance to the precipitation. This also requires two antennas – one to transmit the signal and one to receive the signal.įrequency Modulated Continuous Wave Radar: This short-range measuring radar set also uses two antennas – one to transmit and one to receive the signal. Continuous Wave Radars are typically used with competitive sports. Unmodulated Continuous Wave Radar: This radar can return frequencies that are shifted away from the transmitted frequency based on the Doppler effect when objects are moving. This radar can identify moving precipitation through the use of the Doppler effect. “Clutter” generally refers to fixed objects that the radar beam would always pick up such as buildings, hills or mountains. Moving Target Indication Radar: This is an older type of radar used to discriminate a target against clutter. The pulse is both transmitted and received by one antenna in such a way that the “echo” signal is received before the next pulse is sent. The signal consists of a repetitive train of short-duration pulses. Pulse Radarīasic Pulse Radar: This type of radar is the most common. Let’s take a closer look at the innovations in weather forecasting. Weather technology is constantly evolving. This approach helps meteorologists see what’s behind a heavy precipitation band and more realistically depict what is occurring at the ground level. Another option is to purchase a network of X-Band radars and position them in fixed locations.The radar could be driven to the storm to gain a more accurate depiction of dangerous weather at the ground level rather than using a fixed radar in which the beam would get higher above ground as it got farther away from the radar tower. Since it is small, this radar can be mounted on a trailer or truck, making it very mobile.There are two ways in which most broadcasters would use an X-Band radar: The X-Band radar generally uses a smaller antenna dish and therefore is much less expensive than C- and S-Band radars. This can block the radar from seeing past the initial band of precipitation to identify what could be approaching. These radars are also more susceptible to attenuation as the smaller wavelength does not allow the radar beam to penetrate through heavy precipitation bands. Use cases: X-Band radars have a smaller wavelength that makes them more sensitive to lighter particles. These radars are generally smaller and less expensive than S-Band weather radars, but more expensive than the smaller X-Band radar. However, the beam does attenuate (that is, loses its strength) much more than the longer wavelength S-Band and therefore does not recognize precipitation rates as accurately as the S-Band.

The wavelength of the radar beam can penetrate through moderate to heavy bands of precipitation to identify what is beyond the closest precipitation band. Use cases: C-Band radars are often intended for short-range weather observation but can be used in medium- to long-range precipitation analysis. C-Band radarsįrequency: 4 – 8 GHz, although most weather C-Band radars used for weather operate in the 5.3 – 5.6 GHz range This radar is the most expensive of the three radar bands. However, the ability to see and analyze precipitation returns from greater distances does help the meteorologist generate weather alerts further in advance. Therefore, what is analyzed aloft is not always what one would experience at the ground level. As with all radars, the further the beam is away from the radar site, the higher the beam is above the ground. Use cases: This radar’s longer wavelength allows the beam to penetrate through several bands of precipitation, expanding the range for analysis further than the C-Band radar. This includes the following: S-Band radarsįrequency: 2 – 4 GHz, although most weather S-Band radars operate within the 3.0 – 3.8 GHz frequency Doppler radar can be broken up in terms of wavelength.

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