Omega Block is baking Europe, and humans have amplified it - How does it form and work?

Omega Block is causing Europe’s heatwave, with temperatures reaching 44 degrees Celsius in some regions. It is a powerful meteorological phenomenon featuring a high-pressure system sandwiched between two low-pressure systems. The jet stream in the upper atmosphere bends around them to form a shape that resembles the Greek letter Omega. It traps intensely hot air under it, forming a heat dome, which is what the European countries are feeling at the moment.

How is an Omega Block formed? Is it linked to climate change?

The flow of fast-moving air high in the atmosphere depends on the temperatures at the equator and the poles. If the two stand in sharp contrast, the jet stream flows smoothly from west to east. But if it weakens, the air starts acting in an abnormal fashion. Instead of moving in a straight line, it starts moving wildly in the north and south direction, forming what are called Rossby waves.

The jet stream slows, and the Rossby waves keep growing. A large area within this moves north and, in doing so, pulls warm air up from the tropics. Around this area region two low-pressure areas are formed that dip south, pulling cold air from the polar regions.

This formation is eventually cut off from the main flow of air. The jet stream splits, with one part branching north and the other dipping south. This Omega Block is incredibly stable as all three systems work together to lock each other. But the global jet stream continues to move, bypassing this entire setup. The Omega Block is basically blocked in place, and so the underneath remains virtually unchanged. It stays there until a powerful storm moves upstream.

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In absence of clouds, solar radiation bakes the region

The central high-pressure zone constantly forces air downward, and as it compresses, the heat increases and cloud formation is stopped. In the absence of cloud cover, the Sun shines brightly over this area, and the radiation makes the place hotter. The ground dries out, and as a result, air-cooling evaporation does not happen. The dry ground radiates heat back into the atmosphere, thus making it hotter. Also Read: Analysis: Economic toll of heatwaves and droughts on India amid Europe heatwave

This weather phenomenon is aggravated by human activities. The Urban Heat Island effect has made the planet hotter. With concrete and glass everywhere, the surfaces reflect heat, which gets trapped between buildings. Air conditioners release a lot of hot air, which keeps piling up, worsening the situation.