It All Counts!

Did you make a rain gauge?

If you use it in the winter, it may have to cope with some of this stuff!

Some parts of the world only have rain in the summer, because temperatures are below freezing for the rest of the year.  So just measuring rain doesn’t give the whole picture.  You need to count all types of precipitation.  That’s the overall name for all the ways in which water falls from the sky – rain, snow, sleet, hail.

But snow is light and full of air spaces so you can’t just measure the depth of the snow and add it to the rain.

The amount of moisture in a snowflake depends on the temperature: the colder the temperature the drier the snow.

You have perhaps heard that 10mm of snow is equivalent to 1mm of rainfall.

Well for Britain that is about right, because that is the case when temperatures are just below freezing and that’s usually the conditions when Britain gets snow.  If temperatures really plummet here, then the weather tends to be dry.

So next time it snows, venture out with a ruler.  The maths is easy: just divide by 10 for the approximate rainfall equivalent.