eli5 How do they calculate how many inches of rain has fallen?

Question

Where I live it does not rain a lot. When it does the news always say that it rain 1/8 of an inch or so, but I can see that my pool has increased 2 or 3 inches.

I don’t think this could be from runoff as the edges if the pool are angles away from the pool to prevent runoff from entering the pool. I have also had buckets left out where there is significantly more water than was reported.

Any reasoning for this? Could the rain vary so much that the weather station is just getting a significantly different amount of rain?

Thanks

In: Planetary Science

Answer 1

I used to wonder about this too. My dad put a Tupperware tub and a test tube (flat bottom) in the backyard when it rained. The tub had more volume, but exactly the same height! Amazing!

Until high school when I learned about dimensions.