Hurricanes are intense low pressure areas that form over warm ocean waters in the summer and early fall. Their source of energy is water vapor which is evaporated from the ocean surface.
Water vapor is the “fuel” for the hurricanes because it releases the “latent heat of condensation” when it condenses to form clouds and rain, warming the surrounding air. (This heat energy was absorbed by the water vapor when it was evaporated from the warm ocean surface, cooling the ocean in the process.)
Usually, the heat released in this way in tropical thunderstorms is carried away by wind shear, which blows the top off the thunderstorms. But when there is little wind shear, this heat can build up, causing low pressure to form. The low pressure causes wind to begin to spiral inward toward the center of the low.
These winds help to evaporate even more water vapor from the ocean, spiraling inward toward the center, feeding more showers and thunderstorms, and warming the upper atmosphere still more. The showers and thunderstorms where all of this energy is released are usually organized into bands (sometimes called “rainbands” or “feeder bands”), as well as into an “eyewall” encircling the center of the storm. The eyewall is where the strongest winds occur, which encircle the warmest air, in the eye of the hurricane. This warmth in the eye is produced by sinking air, which sinks in response to rising air in the thunderstorms. The winds diminish rapidly moving from the eyewall to the inside of the relatively cloud-free eye, where calm winds can exist.
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Learn how giant airstreams high in the sky get trapped sometimes – leading to devastating weather extremes on the ground.
Copyright: Potsdam Institute for Climate Impact Research PIK and Climate Media Factory. This video was supported by the German Research Foundation (DFG) and the German Federal Ministry of Education and Research (BMBF).
PIK research on the subject:
– Evidence for wave resonance as a key mechanism for generating high-amplitude quasi-stationary waves in boreal Summer
– Influence of Anthropogenic Climate Change on Planetary Wave Resonance and Extreme Weather Events
– Summertime Planetary Wave-Resonance in the Northern and Southern Hemisphere
– Record Balkan floods linked to jamming of giant airstreams: https://www.pik-potsdam.de/news/press-releases/record-balkan-floods-linked-to-jamming-of-giant-airstreams
– Trapped atmospheric waves triggered more weather extremes: https://www.pik-potsdam.de/news/press-releases/archive/2014/trapped-atmospheric-waves-triggered-more-weather-extremes
– Cold, hot or dry: Persistent weather extremes associated with decreased storm activity: https://www.pik-potsdam.de/news/press-releases/cold-hot-or-dry-persistent-weather-extremes-associated-with-decreased-storm-activity
– Summer storm weakening leads to more persistent heat extremes: https://www.pik-potsdam.de/news/press-releases/summer-storm-weakening-leads-to-more-persistent-heat-extremes
– Record-breaking heavy rainfall events increased under global warming: https://www.pik-potsdam.de/news/press-releases/record-breaking-heavy-rainfall-events-increased-under-global-warming
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