Meet Daniel, the deadly ‘nightmare’ hybrid storm that devastated the Mediterranean

Subject: Geography

Section: Physical geography

Context:

The Mediterranean Storm Daniel that hit Libya, Greece, Bulgaria and Türkiye, has, so far, been responsible for at least 11,000 deaths.

Medicane:

Storm Daniel initially formed over the eastern Mediterranean and caused extensive flooding in parts of Greece, Bulgaria, Türkiye, and Libya.
Medicane is a hybrid term combining the words Mediterranean and hurricane — and requires specific conditions to form. These conditions are:
- Relatively closed ocean basin
- Cold air from north
- Warmer air from south
- Relatively dry air
Historical data on medicanes is patchy, and the criteria used to classify them is less exact than traditional cyclones.
They are rare because of the geography of the Mediterranean — a relatively small ocean basin surrounded by dry air to the south over Africa and numerous mountain ranges.
It contains characteristics of both tropical low-pressure systems (cyclones) and the low-pressure systems usually seen in northern Europe.

Impact of Medicane:

Omega block pattern:

The medicane got trapped by something called an Omega block pattern, which is when a high-pressure system gets sandwiched between two lows.
During an Omega block, the wave in the jet stream becomes amplified, displacing the river of strong wind aloft well south.
The result is that weather systems which normally follow the jet from the west to east become stagnant.

How medicane is different from tropical cyclone:

Tropical Cyclone	Medicane
Tropical cyclones require vast open warm oceans, full of moisture	medicane has relatively small ocean basins surrounded by dry air to the south over Africa and numerous mountain ranges.
Tropical cyclones are self-sustaining systems — once they form, they require no assistance from outside the system to support their survival provided they remain over waters at least 26.5 degrees Celsius. The energy is derived from moist air rising off the ocean and condensing into cloud. The change in phase from a gas to a liquid during condensation releases latent heat, which keeps the rising air warmer than the surrounding air, and ensures it keeps on rising and condensing. As more and more air moves vertically away from the surface, the pressure near the ground drops which pulls air in horizontally, which can then rise and follow the same process much like an engine with a limitless fuel supply.	A medicane strengthens when there’s a sharp temperature contrast between the Mediterranean Sea and cold air coming from the north.
The core of a tropical cyclone is warm.	The core of a medicane is cold. It can only survive as long as cold air remains above relatively warmer air over the Mediterranean.
They have relatively longer life span	They typically have a short life span.

Hot seas helped spark storm:

The sea surface temperatures (SST) of the Mediterranean sea was at times more than 5C above average and air temperatures at record highs.
During the peak of a July marine heatwave, the Mediterranean actually warmed to a record average of 28C, easily surpassing the 26.5C threshold required for a traditional tropical cyclone.
This extra heat helped fuel Daniel’s intensification and also provided the system with added moisture from evaporation.
A warmer atmosphere can hold more moisture before it rains. For every 1C increase in air temperature, the atmosphere can hold 7 per cent more water, which eventually leads to heavier rain and more severe flooding.
Tropical cyclones are declining worldwide, but the intensity of the most severe cyclones is increasing.

Source: abc.net