An omega block is answerable for the heatwave which is gripping elements of the UK.
Here, we check out the climate sample – and whether or not local weather change might make it a extra frequent function within the years to return.
What is an omega block – and the way does it get its title?
Blocks can interrupt the traditional eastward development of our climate.
With an omega block, excessive stress – which usually brings hotter and extra settled situations – turns into sandwiched between two low stress methods.
It varieties a form just like the Greek letter Ω, therefore its title.
How does the omega block influence the jet stream?
Weather methods normally transfer from west to east at our latitude, however generally they’ll get blocked when the jet stream weakens and buckles.
The jetstream is a core of sturdy winds excessive above the Earth’s floor which helps to develop and steer areas of low stress across the globe.
When there may be quite a lot of tropical storm exercise within the North Atlantic, this could bend the jet stream, which is what has occurred on this event.
The place and energy of the jet has resulted in a blocking sample the place the excessive stress turns into caught between the 2 low stress methods.
How lengthy can such a block sample final?
Weather blocks can persist for days, weeks, and even months.
One well-known instance was in the summertime of 1976, when temperatures of above 30C introduced drought situations and endured for lengthy intervals.
How is the block impacting the UK and Europe’s climate?
High stress simply to the east of the UK and centred over Scandinavia is permitting a feed of scorching and humid air from the south.
However, low stress areas are affecting both aspect of the Mediterranean, with the remnants of Hurricane Franklin to the west of Portugal and Storm Daniel bringing torrential downpours to Greece.
Temperatures of above 30C (86F) in September have solely occurred a “handful of times” within the UK – and it is going to be the most well liked day of the 12 months if it climbs above 32.2C (89.96F).
Forecasters say it’s possible temperatures will stay over 20C (68F) at evening in lots of areas.
Conditions are set to alter with thundery downpours slowly transferring in from the west afterward Wednesday.
Read extra:
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Is local weather change making these warmth domes extra frequent?
Sky climate producer Kirsty McCabe stated there may be growing proof the jetstream is being weakened by local weather change.
She stated: “Blocked weather patterns such as omega blocks or heat domes seem to be happening more frequently in recent decades, and that could be linked to the effects of climate change on the jet stream.
“There is a few analysis that means the jetstream is weakening attributable to a discount within the temperature distinction between the equator to the pole because the Arctic has warmed at roughly twice the speed as all the globe – scientists consult with this as ‘Arctic amplification’.”
What are the dangers of such a warmth dome?
A cussed space of excessive stress means already heat or scorching air trapped beneath the excessive will proceed to develop into hotter, making a warmth dome.
Kirsty added: “Hot air will rise into the atmosphere, but high pressure acts as a lid and causes the air to subside or sink. As the air sinks, it warms by compression, and the heat builds.
“The floor additionally warms, dropping moisture and making it simpler to warmth much more.
“Until the pressure pattern changes, the high will continue to exacerbate the hot conditions, bringing a risk of wildfires, drought and heat-health issues.”
Are there every other widespread block patterns?
The Met Office says there may be additionally a diffluent block together with omega.
Diffluent occurs when there’s a “split in the eastwards flow” – and might see excessive stress pushed to the north of a low centre within the south, bringing extended intervals of comparable climate.
Source: information.sky.com”