Europe's record-breaking heatwave: What you need to know

Europe is sweltering through its most severe heatwave on record, with temperatures shattering all-time highs across the continent and the heat now shifting east towards the Balkans and Ukraine.

The heatwave is being sustained by what meteorologists call an omega block -- a weather pattern named for the Greek letter because of the shape it creates in the atmosphere. Hot, dry air from North Africa becomes trapped over a region as low-pressure systems on either side prevent it from moving away. The result is that temperatures have been pushed up to 18°C above their seasonal average. Europe is particularly exposed: only about 20% of European homes have air conditioning, and much of the continent's housing stock was built to retain heat rather than shed it.