Our rather depressing weather this week has been caused by two depressions drifting in from the Atlantic. But it could have been worse, especially in the south.

A series of depressions - or areas of low pressure - have been dominating our weather over the past couple of weeks, and the conditions they have produced are typical.

Most often, our low pressure areas begin in the Atlantic, and are carried by south-westerly winds past the west of Ireland and over the Hebrides. The same winds bring tropical maritime air over most of the country, which takes the chill off our weather, but when associated with a cold front may also lead to a good deal of rain.

Typically, as winter approaches, we might expect cold polar air at night time, with perhaps some frost before midnight, then a warm front arriving from the Atlantic, bringing a quick growth of cloud as it hits the cold air. The temperature will then rise, the cloud will thicken, and rain is likely to follow.

The most depressing depressions are those that move from north-west Scotland and travel down the east coast. They build up the waters in the North Sea bringing gales, storm surges and draw in cold winds from Scandinavia or the Arctic. And none of that pleasant tropical air.