Weather measurements from a distance

You don't have to put an instrument in a rain shower or a wind storm to know about the rain or wind. Doppler weather radar installations can tell, from a distance, precipitation - rain, snow and hail - location and intensity as well as wind strength and direction.

Doppler radar

A Doppler radar station at Buckland Park (cc) Fairv8

Doppler radar sends out microwave pulses to a weather target. The weather target reflects the pulse back to the radar, where it can be measured.  The reflection tells us about what sort of rain or snow is occurring at the target. Successive pulses show how the weather is changing, and help to determine wind speed and direction to forecast the future position and intensity of the rain. The distance to the weather target is calculated from the time the pulse leaves to the time it returns.

A weather balloon carries instruments high into the atmosphere to record atmospheric pressure, ambient temperature, humidity and wind speed by means of a small, measuring device called a radiosonde. They send their data back to earth using a transponder.

Weather balloon_82770161

Scientists with weather balloons

Weather balloons may reach altitudes of 40 kilometres or more, but 25 kilometres is more usual. Every day, at over 750 locations around the world, weather balloons are launched twice daily. That's a lot of balloons a year - you do the maths! A basic weather balloon and its transponder cost about £75 to £100.  Does this seem a reasonable data collection expense?

See if you can find out where weather balloons are launched near you. Many University Departments, and the Meteorological Office, can arrange school visits to allow you to be present and observe the balloons going up.

So, that's how raw data is gathered for weather forecasts. But what happens then? It's not enough just to gather the weather data - you need to use that data to predict what will happen to the weather next. Anyone can look out of the window and see if it's raining - people want to know whether it will rain the next day, and the day after next. Go to Using a Computer to Predict the Weather to find out how forecasts are made.

Weather Data Experiment

weather Schools across the UK can report local weather to help improve forecast
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