Among the most widely used and important meteorological instruments worldwide is the rain gauge . The word comes from "pluvio," meaning rain, and "meter," referring to its measurement. Therefore, a rain gauge is a device for measuring rainfall. This rain gauge is incorporated into weather stations and provides valuable information for understanding both the meteorology and climatology of a location. All precipitation is collected by this instrument.
Here you can find out how the rain gauge works and the importance it has in meteorology and climatology.
What is a rain gauge
This device is used to measure rainfall in a specific area over a given period. This rainfall data is recorded to such an extent that it can be used to create a climate profile for the area, as studied in meteorology . All the collected data is then averaged by month and year to see how rainfall fluctuates over time.
For example, if an area has an average annual rainfall of around 500 mm, this is known because rainfall data has been recorded for many years. The first measurements date back to around 1800. A rain gauge can collect data on any type of precipitation, such as rain , hail , snow , sleet, or drizzle. It cannot measure fog or dew, as these are simply condensation. Its main use is to measure meteorological precipitation in an area in order to establish various data points.
Origin
Although it seems more modern, rainfall measurements have been recorded since 500 BC. The Greeks were the first to measure rain. Later, in India, they had actual rainwater harvesting systems. They placed containers and receptacles to collect and measure rainwater. In these cases, rainfall measurements weren't for the purpose of creating records and data to study the climate of a region. They simply helped to improve crop yields.
Each year, rainfall was measured to determine the amount of water available for crops. The need to measure rainfall stemmed from agricultural necessity, hence its connection to climate studies . This is corroborated by religious texts found in Palestine that discussed how rainfall affected the supply of water essential for crop irrigation. Therefore, at that time, water supply and agriculture were the only things that mattered. They didn't need this data for climate analysis or weather forecasting.
Much later, in 1441 in Korea, the first rain gauge, made of bronze and with a standard opening, was developed. This rain gauge served for almost 200 years, until 1639, when Benedetto Castelli, a disciple of Galileo Galilei , managed to make the first rainfall measurements in Europe. This device was handheld and recorded the hourly rainfall level.
The first rain gauge with tilting buckets was invented in 1662. This device served to record not only rainfall data but also meteorological data such as air temperature and wind direction, topics covered by meteorological instruments.
How it works
The device must be placed in an elevated location to accurately record rainfall levels. This way, it won't be obstructed by any obstacles. When taking a measurement, the container gradually collects rainwater, and the reading will indicate the total rainfall in the area.
It is capable of measuring rain, hail, snow, drizzle, and sleet, although it does not measure mist or dew. This is due to the fact that these are condensation phenomena of water droplets and cannot be measured with the marks on the glass. It is cylindrical in shape and has a funnel-shaped part to collect more water.
Types of rain gauge
Manual
This is the most common type. It's a fairly simple indicator of the amount of rainfall in an area. It consists of a cylindrical container with a graduated scale. The height of the water it reaches is equivalent to the precipitation levels, which are related to the density of snow , another important type of precipitation.
Totalizers
This type of rain gauge is one of the most accurate. They are responsible for collecting the water that falls through a funnel. This funnel recirculates the water to a container that is graduated. They tend to be placed at a certain height from the ground and the fall of water is recorded every 12 hours. The only fault with these rain gauges is that the time at which the rainfall occurred cannot be determined.
Siphon
This type of rain gauge allows for fairly accurate measurement of rainfall duration. It consists of a rotating drum that spins at a constant speed. It is graduated with a pen inside that floats vertically. If the pen is not present, it will mark a horizontal line.
Double tipping bucket
This device collects water using a funnel and directs it to a small, double-walled, triangular container, which can be made of either metal or plastic. It has a hinge at the midpoint of equilibrium. Once the expected precipitation level is reached, usually 0,2 mm, the water level in the other container is adjusted to maintain equilibrium, while the first container begins counting again.
The importance of the rain gauge has been recognized since ancient Greece. Although initially only useful for improving agricultural fields, it was important to ensure a supply of food for the population, an essential aspect of the . Over the years, its importance has increased to the point that it is used not only for crops but also for measuring precipitation in order to study the world's climates and diagnose climate change.
I hope that with this information you can learn more about the rain gauge.