Bomb Cyclone Winter Storm

A bomb cyclone, or weather bomb, is a weather phenomenon in which a low pressure storm intensifies rapidly over an area. It is called a "bomb" because there is a sudden drop in pressure at the centre of the storm. Although this phenomenon is not very common, it's not a rare one either. It occurs around 40-50 times worldwide each year, but it goes unnoticed as it occurs in the open seas. When it develops near the land, it can bring huge amounts of precipitation in the form of rain or snow, along with high-speed winds that can disrupt normal life. In recent years, a bomb cyclone has hit the USA a few times, most intensely in the winter of 2022, when it destroyed the infrastructure in many cities and left dozens of people dead.

• The air over a homogeneous area acquires the characteristics of that region. This mass of air is known as air mass. Inside an air mass, there is very little variation in temperature and humidity.
• When two different air masses interact, their boundary zone is known as fronts.
• Horizontal motion of air is known as wind.
• Wind moves from high pressure to low pressure.
• The pressure and velocity of the wind are determined by the pressure gradient and the coriolis force.
• Around a low pressure or high pressure wind tends to move in circulation.
• Around a low pressure, wind circulation is known as cyclonic circulation.
• Around a high pressure, wind circulation is known as anti-cyclonic circulation.
• The direction of wind around such systems in both hemispheres is given in the below table.

Bomb Cyclone: "Bomb" refers to the meteorological term bombogenesis. Bombogenesis occurs in midlatitudes during the winter months, where a cyclonic storm rapidly intensifies and gains strength within a very short span. This happens due to the frontal activity of the cold air mass (formed over the cold plain area) and the warm air mass (formed generally over the warm ocean). When the pressure at the centre of the storm drops by at least 24 millibars over 24 hours, it becomes a bomb cyclone.

In the Northern Hemisphere, it moves in a counterclockwise direction as it is around low pressure. When this pressure system moves, it gains the surrounding humidity and further intensifies.

When it develops in the North Atlantic Ocean, it moves towards the USA and Canada. This low-pressure region is fed by the cold winds coming from the polar region, and when the cyclone intensifies, more air rushes into the low-pressure region. This results in unusually cold conditions in the region where the cold air passes through.

These are known to occur in the midlatitude regions of the Atlantic and Pacific oceans.

A bomb cyclone brings with it a wide array of weather phenomena, depending on the location. It can cause heavy rainfall, thunderstorms, snowstorms, high-velocity winds (up to 80 kmph) etc. This results in disruption of communication, destruction of infrastructure and houses, and loss of human life due to very cold conditions.

The US National Service has warned the general public of the impact of the bomb cyclone. People are advised to stay indoors to avoid any adverse effects of extremely cold temperatures, such as frostbite and hypothermia. Generally, flights are grounded due to blizzards, roads are blocked by heavy snow, and some areas suffer power cuts. Till now, no causal link has been found between the bomb cyclone and climate change. But the experts warn that bomb cyclones, like other weather phenomena, may become more frequent, intense, and extreme due to climate change, as pointed out by the IPCC's Sixth Assessment Report.