Heat Dome

Why in news?

• The Pacific north-west region, known for its moderate climate, is experiencing a record heatwave.

What is a heat dome?

• A heat dome is a essentially a mountain of warm air built into a very wavy jet stream, with extreme undulations.
• When the jet stream — a band of strong wind in the upper levels of the atmosphere — becomes very wavy and elongated, pressure systems can pinch off and become stalled or stuck in places they typically would not be.
• In this case, a ridge of high pressure, which is the heat dome, has become lodged in the Pacific Northwest.
• It is acting as a block in the atmosphere, not allowing the weather to move.

Why are these temperatures so extreme?

• Areas of high pressure, like heat domes, have sinking air.
• This compresses the air on the ground and through compression it heats the air column.
• In addition, winds are moving downslope from the mountains downward into cities like Seattle and Portland; that downward motion causes heating as well.
• These local effects combined with the background warming of climate change, adds intensity to an already strong heat wave.

Prelims Question

Consider the following statements regarding Heat Dome:
1.It is an area of High pressure with sinking air.
2.Jet streams play a crucial role in creation of Heat Domes.
Which of the statements given above is/are correct?
(a)1 only
(b)2 only
(c)Both 1 and 2
(d)Neither 1 nor 2

Answer to the Prelims Question