Rainfall is measured by collecting water in a gauge and reading the depth in millimeters.

The longer version

A rain gauge is essentially a funnel that channels falling water into a narrow collecting tube. Measuring in a narrow tube makes small amounts easier to read, since the same volume reaches a greater depth. The result is reported as a depth in millimetres, independent of the area of the opening.

Snow must be melted before it can be read, and tipping-bucket versions record each small increment electronically as a see-saw container fills and empties. Placement matters: readings run too low in windy or sheltered spots, so gauges are sited in open ground well away from obstacles.

Where this entry sits

Clouds, wind, rain, and storms shape daily life in ways that most people barely notice. This collection explains snow, lightning, rainbows, the turning seasons, temperature, the instruments forecasters rely on, and scraps of old weather lore. The full list sits on the Weather and Climate page, where every entry is listed in order.