Q. Why is this in news?
A. Major cities such as New York and Boston in US are witnessing a “Bomb Cyclone” characterized by the explosive power of rapid drops in atmospheric pressure.
Q. What is Bomb Cyclone?
A.
- A bomb cyclone is a large, intense mid-latitude storm that has low pressure at its center, weather fronts and an array of associated weather, from blizzards to severe thunderstorms to heavy precipitation.
- It becomes a bomb when its central pressure decreases very quickly—by at least 24 millibars in 24 hours.
- When a cyclone “bombs,” or undergoes bombogenesis, this tells us that it has access to the optimal ingredients for strengthening, such as high amounts of heat, moisture and rising air.
Q. Why is it called a bomb?
A.
- Most cyclones don’t intensify rapidly in this way.
- Bomb cyclones put forecasters on high alert, because they can produce significant harmful impacts.
Q. How does it occur?
A.
- Over the warmer ocean, heat and moisture are abundant.
- But as cool continental air moves overhead and creates a large difference in temperature, the lower atmosphere becomes unstable and buoyant.
- Air rises, cools and condenses, forming clouds and precipitation.
Q. Where does it occur the most?
A.
- The US coast is one of the regions where bombogenesis is most common.
- That’s because storms in the mid-latitudes – a temperate zone north of the tropics that includes the entire continental US – draw their energy from large temperature contrasts.
- Along the US East Coast during winter, there’s a naturally potent thermal contrast between the cool land and the warm Gulf Stream current.
