‘Beast from the East’ brings chaos to Britain

The winds are changing: It can take weeks for an SSW to have an effect on Europe’s weather.

Why is it so cold? This week the UK is in the grip of a big freeze as a blast of polar air sends temperatures plummeting to below zero. And some believe climate change might be the reason.

Today parts of Britain are colder than the North Pole. With spring tantalisingly close, the country is in the midst of a spell of bitingly cold weather. Up to eight inches of snow will hit eastern England by tomorrow.

Temperatures dropped to -9.2°C on Sunday, while the wind chill factor will make temperatures feel as cold as -15°C; so cold that it will cause power cuts and hit mobile phone networks. Commuters have been urged to get home by 6pm as the country faces travel chaos.

This icy weather is the result of a phenomenon called a “sudden stratospheric warming”.

The stratosphere is the second major layer of the Earth’s atmosphere. It starts around six to eight miles above the surface and ends at 31 miles. Most of our weather comes not from the stratosphere, but from the troposphere below.

During the winter, a blob of extremely cold air spins clockwise in the stratosphere above the Arctic. It is particularly cold due to the total lack of sunlight hitting the Arctic at this time.

If the cold blob starts to spin slower, the air will rush back inwards. Think what happens when you are stirring a cup of tea very fast, and then stop.

As it slows down, this air sinks through the atmosphere, becomes warmer, and then even starts to spin the opposite way.

Britain usually experiences westerly winds. This means they come from the west, not that they head towards the west. This is because of the northern hemisphere’s jet stream, which brings warm air across the Atlantic, and explains why the UK is much warmer than its latitude would suggest.

But a sudden stratospheric warming reverses this jet stream, and means that Britain’s weather starts coming from the east - meaning the freezing mass of Siberia. So while the west of the British Isles usually sees the most extreme weather, this time the eastern part of England that has born the brunt of this cold snap.

Scientists predicted that such events would become rarer due to climate change. But in fact the opposite has happened. Is this big freeze a purely natural event?

Global warning

Climate change plays a part in almost every weather event, say many scientists. In recent years over North America and Europe, such events have increased in regularity. Global warming causes hotter air to build in the atmosphere, altering jet streams and changing weather. It might have happened anyway, but climate change has helped.

Don’t jump to any rash conclusions, reply others. Records of extreme weather were patchy up until a few decades ago, and so we have surprisingly little data to analyse. Britain has seen far more extreme winters in centuries past. And the incorrect predictions prove one thing: no-one really knows what’s going on.

You Decide

  1. Is it right to draw a link between climate change and individual extreme weather events?
  2. Is it boring to talk about the weather?

Activities

  1. In groups, design an infographic to illustrate an aspect of climate change.
  2. Research the history of predictions about climate change. Find one forecast which was correctly predicted, and another incorrectly. Explain what was forecast and what actually happened.

Some People Say...

“A change in the weather is sufficient to recreate the world and ourselves.”

Marcel Proust

What do you think?

Q & A

What do we know?
Britain is in the grip of a cold snap of weather, caused by a phenomenon known as a Sudden Stratospheric Warming. This occurs when a rise in the stratosphere’s temperature causes jet streams to change direction, meaning that Britain’s weather starts coming from the east. We know that these events have occurred particularly regularly over recent years.
What do we not know?
To what extent we really can draw links to climate change from one naturally occurring weather event. Scientists have predicted that climate change will cause more extreme weather at both ends of the spectrum, although the general trend is a slight increase in global temperatures.

Word Watch

Colder than the North Pole
The North Pole and parts of Greenland are predicted to be almost 30°C warmer than their usual levels, reaching a balmy -5°C.
Troposphere
The troposphere reaches down to ground level, and is where all clouds are formed. It contains approximately 75% of the atmosphere's mass and 99% of the total mass of water vapour.
Lack of sunlight
At the North Pole, the polar night begins as the Sun sets around the Autumnal Equinox in September. It lasts for about six months until the Sun rises again around the Spring Equinox in March when six months of Polar Day, or Midnight Sun begin.
Jet stream
There are two types of jet streams: stronger polar jets and weaker subtropical jets slightly above them in the atmosphere. The northern hemisphere and the southern hemisphere each have a polar jet and a subtropical jet.
Much warmer than its latitude would suggest
The UK is level with the Canadian island of Newfoundland. The average February temperature in Newfoundland’s capital, St. John’s, is -4.9°C.

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