Radars are used to effectively monitor and report weather conditions do so by sending out electromagnetic waves much like those used by wireless computer and mobile phones on a network.
These signals are transmitted by a series of short pulses and are reflected by any objects on their directional path thus reflected to the origin of the signal which in this case would be the weather radar.
Weather radars are specifically designed to detect the presence of rain drops, snow, and even the presence of hail from the intensity of the reflected radio waves a person can easily give an estimation of the location of the event and how heavy it is.
Doppler radars are not only able to perform this specific function but are also capable of measuring the current speeds of the particles from which the signals are reflected. When precipitation occurs within the atmosphere it is affected by wind speeds.
As a result the Doppler radar can effectively measure their movements, whereby providing information relative to those existing wind speeds their direction and the intensity and location of the rainfall. With the ability to successfully capture and record this information, weather forecasters are thus better equipped to gain a much better understanding of the current weather.
The Doppler radar achieved its name due to the process used in which the radar measures the respective velocities. Proposed in 1842 by Christian Andreas Doppler, the Doppler Effect states that the frequency of a wave at any given point varies with the motion of the source of the signal relative to the observer. When observed this effect was noticeably more existent when using sound waves which can be easily measured at any instance of observing the lowering in pitch.
Such an example can be seen when an emergency vehicle such as a fire truck and the vehicle can be seen moving past a point. This particular application known as the Doppler Effect has been widely used and has even been implemented in applications including calculating the speeds of cars on the highway and even the speeds of a pitched ball during a baseball game.
Current wind velocity at any given period of time can be seen as a combination of two specific components generally referred to as transverse and radial components. However the radar is only able to effectively monitor and make calculations based on the radial component. With this limitation, the radar is only able to record only a fraction the current wind speeds directed away or towards the radar.
The Nyquist velocity is the maximum velocity recorded and displayed by the Doppler radar independent of the length of the frequency and specific wavelength pulses sent from the radar.
The Doppler radar emits electromagnetic waves traveling at the speed of light allowing the radar to easily calculate the distance of the reflected particle within a single pulse.
The Doppler radar has the ability to emit a maximum of over 1000 pulses per second, however as the pulses are exceedingly short, the Doppler radar will spend over 99 percent of its time listening for reflected pulses.
With a rate of 1000 pulses per second the maximum distance achievable by a pulse to encounter and successfully return to the radar is 150 kilometers.