RAINFALL
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.