Rain gauge

What is a rain gauge? A rain gauge (also known as undometer, pulviometer or an

ombrometer) is a type of instrument used by meteorologists hydrologists to gather and measure the amount of liquid precipitation over a set period of time.

Purpose of rain gauge the purpose of rain gauge is simple to measure how much rain has fallen

in the last 24 hours.

The gauge is re-set every 24 hours for accuracy and if rain fall exceeds expectations a graph is plotted to measure how much rain should fall on average for the following few days.

types of rain gauges

standard rain gauge

Tipping bucket rain gauge

Optical rain gauge

Acoustic rain gauge

Standard rain gauge Standard rain gauge consists of a funnel emptying into a

graduated cylinder,2cm in diameter, which fits inside a larger container which is 20cm in diameter and 50cm tall

When measurements are taken the height of the water in the small graduated cylinder is measured.

Standard rain gauge

Tipping bucket rain gauge

The tipping bucket rain gauge consists of a funnel that collects and channels the precipitation into a small see-saw like container

After a pre-set amount of precipitation falls, the lever tips, dumping the collected water and sending an electrical signal

Modern tipping (rg) consists of a plastic collector balanced over a pivot. When it tips it actuates a switch, which is then electronically recorded or transmitted to a remote collector station

Tipping bucket rain gauge

Optical rain gauge

These have a row of collection funnels

In an enclosed space below each is a layer diode and a photo transistor detector ,when enough water is collected to make a single drop it drops from the bottom, falling into the laser beam path.

The sensor is set at right angles to the laser so that enough light is scattered to be detected as a sudden flash or light.

The flash from the photo detector then read and transmitted or recorded

optical rain gauge

Acoustic rain gauge the acoustic disdrometer is also known as hydrophone, it is able to

sense the sound signatures for each drop size as rain strikes.

Selected moments of the drop size distribution yield rainfall rate, rainfall accumulation and other rainfall properties.

Acoustic rain gauge

Importance of rain gauge a rain gauge measures rain fall and other precipitation like heavy rains

dew and mist.

It is important to know how much moisture and water is present in the ground.

This helps people like farmers and companies who sell food goods and other users.

Why rg is made up of copper A rain gauge can be made up of many things but the use of copper

is advantageous as it fabricates easily and inexpensive.

It is also resistant to corrosion.

Copper is also poisonous to moulds and slimy things that might want to grow on it.

facts about rain gauges

They don’t work in hurricanes. No water will get collected in the cylinder because of too strong winds.

Most rain gauges are inaccurate because of winds.

Rain gauges don’t work in certain temperature ranges because precipitation gets freeze.

Unit of rain gauge is mm(usually).

Any questions