Rain gauge is the instrument used to measure the amount of rainfall in a day.It should be made of impermeable material which can’t absorb water.
How It’s Used/Works
It’s taken to an open space to prevent water from dropping into the funnel. Its sunk into the ground to prevent evaporation The funnel top is left 30cm above the ground to prevent splashes of water and run off.
After 24 hours water is emptied into the measuring cylinder. The reading of the amount of rainfall is got from the measuring cylinder in millimetres. The figure represents the millimetres of water falling on each square millimetre of the ground. It could be used to measure snow fall by melting it before the readings are gotten.
Calculating Rainfall
- Monthly Rainfall Total
-Sum of rainfall recorded in a month.
- Annual Rainfall Total
– Sum of monthly rainfall totals for 12 months.
- Mean Monthly Rainfall
-Sum of rainfall totals for a particular month over several years divided by the number of the years of observation.
- Mean Annual Rainfall
-Sum of mean monthly rainfall for 12 months of the year.