Latest News

What is the "Omega Block" causing Europe's intense summer heatwave?

What is the "Omega Block" causing Europe's intense summer heatwave?
What is the "Omega Block" causing Europe's intense summer heatwave?

A weather pattern called an omega block is sustaining the intense heatwave that has engulfed Western Europe and caused more than 40 deaths in France alone.

What you need to understand about omega 'blocks' and whether they could be more common in the future due to climate change.

What is an 'OMEGA BLOCKS'?

The Greek letter O is the shape of an omega block, with a bulge between two low pressure systems that are cooler and warmer.

The "blocking element" refers to the way in which warm, high-pressure air becomes stuck. In normal conditions, the Jetstream carries weather systems from west to east.

The pressure systems are isolated when the flow is disrupted by an omega block. These'slow-moving patterns' are caused by weaker steering winds, and by temperature contrasts within the atmosphere.

This results in hot still air being trapped over the same region. The average lifespan of an Omega block is between 3 and 10 days. However, they can last for several weeks.

WHAT HAPPENS WHEN AN OMEGA BLOCKS?

Conditions become hot and dry in the?area of high-pressure?in the middle. High pressure suppresses the formation of clouds, which results in clear skies and sunny skies, which allow temperatures to rise. Conditions like this are baking France, Spain and other countries where temperatures have risen above 40 degrees Celsius.

Low-pressure zones flanking the hotspot are likely to experience cooler and rainier conditions.

According to the UK Met Office, Britain is located on the boundary of a high-pressure system and a cooler air mass in the northwest, causing intense heat in south and east and cooler and wetter conditions north and west.

IS CLIMATE CHAIN RESPONSIBLE FOR THIS? Scientists are not yet in agreement on?how climate changes?affect the frequency of events such as this one. Global scientific consensus, however, is that climate change increases the frequency and intensity of heatwaves.

Since pre-industrial times, greenhouse gas emissions mainly from coal, oil and gas burning have warmed the earth by about 1.3 C.

Heatwaves are more intense when the baseline temperature is higher. Clair Barnes, research associate at Imperial College London in extreme weather, climate and climate, says that Europe now experiences 'heatwaves 2 to 4 degrees hotter than would have occurred without human-caused warming. When patterns such as omega blocks are observed, the heat that results can be much more intense. (Reporting and editing by Richard Lough, Ros Russell and Kate Abnett)

(source: Reuters)