‘Rain, rain go away. Come again another day.’ Have you ever wondered how much rain falls during a quick shower or a big thunderstorm? In this lesson, you will learn about rain gauges and how they help us measure rain.
Have you ever heard the saying, ‘It’s raining cats and dogs!’? People use this expression when it’s raining really hard outside. Unlike the saying, we don’t measure rain by what types of animals fall from the sky!
Since the time of the ancient Greeks, people have kept records about the rain to help them understand the world around them. Records about rain also help people decide which seasons are best to plant and harvest crops.
Meteorologists are scientists that use a lot of different instruments to learn more about and predict the weather. One of these instruments is a rain gauge, which measures how much rain fell during a rain storm.
Standard Rain Gauges
A standard rain gauge has a graduated cylinder, or a cylinder with measurement marks on the side and a funnel on top. When rain falls, it goes into the funnel and collects in the graduated cylinder. Many rain gauges have two cylinders: a smaller cylinder inside of a larger cylinder.
This way, if the small cylinder fills up, then the extra rain will collect in the large cylinder and provide an accurate measurement of the total rainfall.
Rain gauges usually measure rain in millimeters or inches. By looking at the level of water in the graduated cylinder and the measurement lines, you can determine the total rainfall.
For example, if it rained hard all day and you looked at your rain gauge, the level of water might rise to the 1/2 inch mark. This means that 1/2 inch of rain fell on the ground in that spot.
Other Types of Rain Gauges
There are many different types of rain gauges available other than the standard rain gauge. For example, an optical rain gauge uses light beams to determine how much rain has fallen and how quickly. As the rain hits the light beam, the machine is able to determine how much rain is falling through the beam and how quickly it is falling.
A tipping bucket rain gauge has a funnel with a seesaw-like spout. As a rain drop goes down the funnel, it falls on one side of the seesaw and into the container. The next rain drop then falls on the other side of the seesaw. By counting the number of times the seesaw moves back and forth, a person or machine can determine the amount of rain and how fast it is falling.
Another type of rain gauge uses a collection container and a sensor to weigh how heavy the precipitation is.
This particular type of rain gauge not only weighs rain but also snow and hail.
Limitations of Rain Gauges
Different factors may interfere with a rain gauge’s ability to accurately measure rainfall. For example, during storms with extreme winds, like hurricanes, rain may be blown out of the container. Additionally, in cold temperatures, water can freeze inside a rain gauge, causing the water that falls after it to splash out of the gauge.
Finally, it usually does not rain the same amount in every location affected by a rain storm. Therefore, the rain gauge can only measure the rainfall in the exact location where it is stationed.
Rain gauges are used by meteorologists to determine the amount of rain that falls in a particular area.
Although there are different types of rain gauges, many of them use a graduated cylinder to measure rainfall. Rain gauges can be affected by wind, extreme temperature, and location.