Rainfall calculations - how's that done then ?

[sinnoc00]

When you hear a weather forecaster say that there will be 2 centimetres of rainfall, how do they calculate this ? Is it any more scientific than putting a bucket out and measuring how full it gets ?!!

[ugly_bob]

nope, no more scientific than that

[Catso]

Although it does sound a bit odd, it's a perfectly sensible measurement. No matter how big or small your bucket, the same depth of rain will result. Think about it.

The only proviso is that the area used for collecting should be the same as the area used for measuring IE using a funnel into a jug would distort the measurment.

[Loosehead]

It's known as a rain gauge and it is a specific diameter but yes, essentially a bucket and a gauge.

[THECORBYLOON]

A funnel is usually used, with the water collected in a tube. If, for example the area of the funnel opening is 10 times lthat of the tube, it will collect 10 times the amount if there were no funnel. That means the markings on the tube are increased by the same ratio. One inch of fallen rain is the same as 10 inches in the tube. The greater the ratio, the more accurate the measurements.