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

  1. Monthly Rainfall Total

-Sum of rainfall recorded in a month.

  1. Annual Rainfall Total

– Sum of monthly rainfall totals for 12 months.

  1. Mean Monthly Rainfall

-Sum of rainfall totals for a particular month over several years divided by the number of the years of observation.

  1. Mean Annual Rainfall

-Sum of mean monthly rainfall for 12 months of the year.

See also  AIR MASSES

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