How Does a Rain Gauge Measure Rainfall | The Weather Station

Modern technology has invented a lot of things that help us in many ways, and one of the inventions are the weather instruments. One of the primary apparatus of the weather station is the rain gauge.

Rain gauge helps us to track the rainfall and through the readings of this instrument the humidity, rate of precipitation can be predicted. Many of us might know about a rain gauge but what we don’t know it’s working procedure.

Without any delay, let’s give an overview of the measurement and working procedure of the rain gauge.

What Is A Rain Gauge?

Before getting into how a rain gauge works, let me give you a brief and clear idea of the rain gauge. The rain gauge is also known as a pluviometer and odometer.

It is an instrument used by meteorologists or hydrologists to gather first and measure the rate of liquid precipitated over a definite period. The precipitation can be snow, rain, hail or sleet.

Through this instrument, the depth of the gathered liquid is measured in millimeters (mm) over a specific unit area. Here one millimeter is equivalent to one liter of rainfall per meter square. That is the unit of the measurement of rain gauge is millimeter or liter per square meter.

Different Parts Of The Rain Gauge

The rain gauge generally consists of two main parts. They are:

• A funnel that takes part in collecting the liquid to be measured. The interior funnel is surrounded by a special coating that reduces the wetting of the surface.
• The mechanism of receiving and measuring the water where the funnel is placed at a certain height in such a way that there is no water spill.

Types And The Working Procedure Of Rain Gauge

Different types of rain gauges have developed over time. Considering place, working process, cost, and necessity, people, as well as different weather stations, use different types of rain gauge. Some examples are:

Non-Recording Rain Gauge

The most widely and commonly used rain gauge is this type. This type of gauge is preferred the most by the meteorological institutions.

Non-recording rain gauge consists of 127mm of the cylindrical vessel and a base of a diameter of 210mm. At the top of the funnel, there is a circular brass that can fit the vessel well.

There is a receiving bottle of 75-100mm which is thinner than the cylinder and connected to the base. The funnel is inserted on the neck of the bottle for collecting rainfall.

Here, the receiving bottle has the capacity of collecting 100mm water. So, during heavy rainfall, the vessel would be exceeded frequently and hence, the rainfall should be measured for 3-4 times the initial reading by a graduated measuring glass.

The instrument should be kept clean all the time especially in dry weather for the accuracy of the result and for keeping it free from dust.

Recording Rain Gauge

Recording gauge can be subdivided again into three types, and they are:

Weighing Bucket

This is the most common self-recording gauge. The receiver bucket of this type is supported by the spring or weighing mechanism.

If there is heavy rainfall, then the weight of the bucket increases and the increased weight is shifted to a pen that records the measurement on a clock-driven chart.

The curve or graph that is formed by plotting the accumulated rainfall in the receiver bucket is called the mass curve that helps to know the information about different rainfall.

Tipping Bucket

This is a type of gauge that is used commonly in the home weather station. The collector funnel of this bucket is made in such a way that it is connected with two containers horizontally where the rain is directed. When the bucket reaches the required weight, the bucket is flipped and discharged due to the gravitational force.

The number of flips or switchovers is measured by the optical system, and this record gives the measurement of the precipitation.

One major benefit of using this instrument is that along with the rainfall it measures the rate of precipitation. But as usual, every material comes with a drawback. If the precipitation becomes high, then jam occurs that results in an inaccurate measurement of the rainfall.

Again, the flip of the bucket occurs when the water reaches a certain weight. If the rainfall is not enough to achieve that weight, then the amount of accumulated water will not be counted.

Optical Gauge

This gauge has a funnel on the photodiode. The measurement is done by visual irregularities. Here the drops of rainfall are directed by a beam of light and by measuring the intensity of the light the rate of precipitation is measured.

Conclusion

We become victims of different natural disasters over the years like hurricanes, tornadoes, storms, etc. The rain gauge helps to give an alarm beforehand, along with the other weather instruments.

Moreover, it helps to keep track of the rainfall, the time and the type of coming rain can also be analyzed through the result given by the rain gauge. For these reasons, one of the primary instruments for every weather station is the rain gauge.

The above information will help you to get an idea about the rain gauge as well as its working procedure.