ABSTRACT
The pattern of rainfall and the temperature are often taken as a concise description of the climate of a place. Kinds of precipitation include drizzle, snow and hail. A particular aspect of rainfall is its acidity, arising from gases dissolved in the drops. There have been many suggestions of rhythms in the amount of rainfall, perhaps linked to the frequency of sunspots or phase of the moon. The only reliable rhythms are daily, seasonal and perhaps biennial. Floods are rivers which overflow their banks. This happens when there is an abnormal runoff from a wide catchment area into the river — from heavy rains or the rapid melting of snow upstream. A drought can be as damaging as a flood, but affects a whole region and not just the low-lying parts. A factor which does certainly increase the chance of drought is an unusually low sea-surface temperature (SST) nearby.
