How to Read a Weather Radar Map

With a weather map forecast app or website, it is possible to see a live weather map. That means clouds and rain are shown to move across a specific territory. How is this possible, though?

Data for such animated maps are found from weather radars throughout the world. These radars can predict snow and rain, as well as other precipitation. However, they’re also used for wind and extreme weather (tornados and thunderstorms).

You’re going to learn how to read a weather radar map, how they work, what they do, and more. When you’re finished, please consider sharing this on social media. That way, your friends know what to do, too!

What Are Weather Radars? Why Are They Needed for Weather Forecasting?

A weather radar is sophisticated meteorological equipment. It is used to determine where water-bearing clouds are and their trajectories. That means these radars are essential to predict tornados, heavy rains, thunderstorms, snowfalls, and other dangerous weather conditions.

Weather radars measure wind speed, as well. A wind radar can detect a tornado and accurately calculate when any bad weather might come to a region or city. Plus, it lets others see the path of the storms to prepare for them.

The term “radar” started to be used in the early 1940s, and it’s an abbreviation that stands for Radio Detecting and Ranging. The first ones appeared around 1950 in Canada and the United States.

These radars are real and are about the size of a four-story building. There’s a big ball at the top of it. This is the antenna shelter. The radius of action averages about 200 to 250 kilometers. Typically, there’s a small building by the radar so that employees can monitor it and make sure that it’s running correctly. Don’t worry if you see it in a field; it’s supposed to be there!

This machine has the following components:

  • Transmitter to make the energy pulse
  • An antenna that works with the pulses
  • A radar processor to analyze the radar information
  • Receiver to detect the signals
  • Display to show various data

An interactive radar is what a person sees on their smartphone or computer. It can give them real-time and “right now” weather forecasts about precipitation and other things.

The data shown on a live weather radar is used to monitor potentially dangerous situations each day. It can also be used by government organizations around the world to process and collect meteorological data for research and forecasts. Here are some examples:

  • NOAA (US National Oceanic and Atmospheric Administration)
  • Meteorological Service of Canada
  • Met Office UK

From that information, meteorological and rescue services from other countries can tell the population what’s going on and when to take appropriate precautions.

Radar data is crucial to ensure people’s safety in industrial plants and settlements (hydropower plants) and to help prevent property damage from bad weather.

It’s important to note that while all services use the data from the same weather stations and radars, the forecasts can differ. This is because one service might use different calculation systems and meteorological models.

Weather radar

The Main Weather Radar Types

There are various radar types, and each one has its own characteristics. However, the main one is called a Pulse-Doppler radar. Most modern radars are Dopplers.

Why did they get this name? Such radars use the Doppler Effect, which is named after Christian Doppler, an Austrian physicist. He described it back in 1842. If the distance between the wave source (radar) and the object on which the waves are reflected (the drops in the atmosphere) changes, then that is going to change the reflected wave frequency.

From those changes, it’s possible to calculate the distance from the thunderclouds/tornados to the radar. People can also determine the speed and direction of bad weather movements.

The Doppler Effect is often seen in daily life. When an ambulance approaches, you hear the siren, and it gets louder and louder. As the volume rises faster, the vehicle is approaching more quickly, too.

Live Doppler radars have actually been used for more than 30 years to study wind and thunderstorms. Now, they’re widely used as weather radar systems. Modern equipment determines the location and existence of atmospheric objects, but it also detects speed. With that, Doppler radars can remove any reflections from the earth that might interfere with the research.

How Does the Radar Work?

All-weather radars (including Doppler) work on the reflection principle or echo:

  • The radar antenna can emit a directional radio signal with wavelengths of 1 to 10 cm into the atmosphere as high-power, short-term pulses.
  • Those impulses meet objects in the atmosphere, such as turbulent currents, raindrops, and surfaces. They are reflected from those and returned to the device, losing energy along the way.
  • Special software is used to measure the strength of the radiation reflection and how long it takes to get returned.
  • From that data analysis, specialists can build a meteorological model to create the forecast shown on television and online.

Radars can send out strong signals, but they get weak ones back. This happens because the signal can travel back and forth, and it gets tired along its journey and loses energy.

The difference in speed and power for the pulses is what makes it possible to find out the speed, position in space, density, and other parameters of the obstacle, such as a thundercloud or airplane.

On top of that, the snowflakes and raindrops are small, moving constantly, and don’t reflect a signal well. Therefore, weather radars have to be in the right location, and remoteness from interference and electronic noise is imperative.

Do Weather Radars Have Limitations?

While radars bring a lot of benefits, they do have limitations that make it nearly impossible to get perfect weather radar, such as:

1. Data from national weather radars isn’t accurate because of interference. It happens when the objects reflecting the radio beams are tiny.

2. The requirements for the radar’s location are very strict. Nothing can interfere with the signal transmission, or it doesn’t work.

For radars to be accurate, there can’t be high terrain elevations or buildings within their radius. Mountainous terrain makes it physically impossible to scan the underlying surface. Very large buildings by the radar can affect the radar measurement’s accuracy and cause a shading effect.

Separately, interference from wind farms is noted. One study showed that one wind turbine had a significant impact on the performance of the Doppler radar. In fact, it hurt performance even at a long distance.

For example, at a distance of fewer than 10 km, the radar data contained errors everywhere. This happened even at a 180-degree angle relative to the sector for the wind farm’s location. Therefore, wind turbines affect the weather radar’s reception and shouldn’t be neglected.

3. National weather radars are very expensive to maintain and build. Some countries don’t have space or resources to maintain a network of radars.

How Many Weather Radars Are There in the World?

There aren’t many weather radars out there. In total, there are only about 1,500 operating radars. That isn’t a lot! In comparison, there are about 40,000 meteorological stations within the world, and these are the main places to collect weather information. Data from the radars can be received faster than from a meteorological station.

To obtain the most accurate weather data on radar, they have to be networked. They’re combined into national and local radar networks that are spaced evenly throughout the territory.

These networks operate all the time and cover big areas in real-time. That way, they can warn people early of hazardous weather phenomena. As the distance increases from the radar, that beam moves from the ground and gets wider. That means there’s less accuracy from the observations.

NEXRAD is the world’s largest local radar network, and it’s in the United States. It’s got 160 Doppler radars. This system provides coverage for most of the US, though it doesn’t help with the western areas.

In Russia, there are 36 radars, and two of them are in Moscow and found at airports. This is especially important because aviators need to receive the most updated information.

What’s a Live Weather Radar Map?

The live weather radar map contains real-time, processed radar data with a minor delay. It’s displayed electronically on a map. Generally, it shows areas of precipitation with different colors, and it all moves.

Typically, the precipitation type and intensity are shown in various colors. Some applications may display it differently. For example, some might show rain as light blue and snow as dark blue. However, another application might change the colors.

Previously, radar data and weather forecasts were tabulated. That’s not convenient when comparing forecasts for different areas. A person might have to open a tab for one city, view that, remember it and close it, and open another city tab.

Live weather maps make it easier to track weather movement and compare forecasts. It’s easy to see how the hurricane moves on a map to determine where it’s going to hit and what’s bypassed. It’s harder to do that with graphs and tables.

How to Read a Live Weather Radar Map

Each application has its own legend (the thing that explains what the colors mean). Green is often indicated for rain, with blue being for snow. Red often shows tornados or hurricanes.

There’s also a time scale. People can view what has happened, what is happening now, and what might occur a few hours in advance.

It is also possible to move the map to see other locations. That way, a person can see where the storm started and follow its progression up to their area and beyond. This is very helpful for people on a hike or who move around a lot.


Learning how to read a weather radar map is essential, but it’s also nice to know how they work. This article contained tons of useful tips on reading radar maps. Now, please share it with your friends so that they can get the same advice and know what to look for from a radar map.

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