In meteorology and weather forecasting, it is essential to know the precipitations that are going to take place in a specific area well in advance so that, if necessary, take preventive measures in a dangerous situation. To do this, there are devices that can indicate and continuously monitor the rainfall in a specific area. It is known as rainfall radar.
Do you want to know how they work and how they are used to predict rainfall?
Rain Radars
For those who don't know yet, the word radar comes from the English acronym radio detection and ranging. This stands for 'radio distance detection and measurement'. Radars are in many places, such as speed cameras. In meteorology, various types of radars are used to monitor the situation in the upper layers of the atmosphere and know the evolution of atmospheric systems. For more information on radar types, you can check out this article on storm radar.
The rada uses a system of electromagnetic waves to be able to measure the distances, directions, altitudes and speeds of objects, both static and moving. In this way, they are able to monitor vehicles, airplanes, ships, etc. In this case, they are used to evaluate meteorological formations and have a continuous monitoring of the movement of the clouds.
Its operation is quite simple. They generate a radio pulse and this is reflected in the target, being received from the same position of the emitter. Thanks to this you can get a lot of information about the location of the clouds, their density and shape, if they are growing, if they are going to cause some kind of precipitation, etc.
Elements of a radar
Source: Euskalmet.com
All radars need several types of elements for their operation to be correct. The use of these electromagnetic waves that the radars send allows to visualize the objects at great distances. Best of all, not only can you know the location of clouds in the spectrum of visible light, but it also provides information in sound.
The main components that radars need for their operation are:
- The transmitter. It is used to be able to generate the high frequency signals that will later be sent.
- Antenna. The antenna is responsible for sending and receiving that high frequency signal that will provide information about the position of the clouds.
- Receiver. This apparatus is used to detect and amplify the signal picked up by the antenna so that it is legible.
- A system that allows to show the results obtained from the measurements.
Doppler radar
Doppler radar is a system capable of measuring numerous variables on the same object. It is able to provide information about the course, distance and altitude of an object, in addition to being able to detect up to its speed. With this type of radar, meteorologists are able to understand the dynamics of a cloud and thus determine its direction, shape, and the probability of precipitation. For more details on how these radars work, visit this article on what is meteorology and its relationship to weather forecasting.
Pulsed Doppler radar is based on the emission of three pulses at a certain frequency and, using the Doppler effect, the relative transverse velocity of that object to be measured can be known. Since these types of radars do not measure distances well, they are not very useful to know the exact location of the object.
Theoretical foundation of radar
Source: pijamasurf.com
To correctly understand the operation of a precipitation radar it is necessary to know the theoretical foundation. These radars act as a function of the movement of objects with respect to the radar in the component perpendicular to the direction of light. This movement produces an alteration in the frequency of the electromagnetic wave that they produce when light falls on them. That is, when sunlight falls on the object to be studied, the frequency of the electromagnetic wave that it emits is varied. With this variation, the radar is able to know the position, course and speed of the object, in this case, a cloud.
When the cloud approaches the radar it positively influences the frequency of the previously emitted waves. On the contrary, when an object moves away from the radar, it has a negative influence. The difference between the emitted and received frequencies are those that allow calculating the speed at which the object is moving.