What’s causing the unprecedented heatwave in Canada?

As western Canada faces a dangerous record-smashing heatwave, senior climatologist for Environment Canada David Phillips says a “heat dome” is engulfing the region.

“This dome stretches half way up to the atmosphere and it is a cap, a lid, putting a lid on top of boiling water, and inside that lid there’s no, no weather comes in, it’s just progressively warmer, and because it’s high pressure … that air squeezes each other and little air molecules jiggle and jangle and create heat and it doesn’t escape – that heat stays within that kind of dome,” he tells broadcaster CBC.