What is the Meaning and Importance Behind a Tropical Cyclone's Outflow? (Imagery credit: Himawari-8 Satellite Imager)
DISCUSSION: Year in and year out, millions of people all over the world bear witness to the formation of tropical cyclones in tropical ocean basin across the globe. During some of the more intense tropical cyclones which form during a given year, there are often some neat satellite imagery-based signature features which can be greatly appreciated even by the general public. One such example of an interesting feature which will often occur in association with tropical cyclones of variable intensities, but most often in association with major hurricanes (i.e., across the tropical Eastern and/or Central Pacific Ocean as well as the tropical Atlantic Ocean is upper-level outflow.
Upper-level outflow associated with a tropical cyclone is particularly interesting since it will always flow in the opposite direction from the more intense cyclonic (anticyclonic) winds which occur with tropical cyclones which form within the Northern (Southern) Hemisphere. However, the big question which many people will often inquire about in association with upper-level outflow tied to more intense tropical cyclones is why the upper-level winds from in the opposite direction of the low/mid-level wind flow regime. As is often the case with many interesting scientific conundrums in life, the answer to this question is actually very simple. And that answer is a result of a basic atmospheric dynamics principle and fundamental law of atmospheric physics. This basic atmospheric dynamic principle is the fact that above any low-pressure center is a high-pressure center and above any high-pressure center is always going to be a nearby low-pressure center. Effectively, this fundamental principle is what allows the atmosphere to always remain at or closer to a dynamically-stable state of atmospheric balance over both shorter-term and longer-term periods.
When it comes to observing upper-level outflow associate with a tropical cyclone via satellite imagery, it is often photogenic and almost mesmerizing to watch. Moreover, upper-level outflow is often found to be quite attention-grabbing despite the storm encapsulated within the symmetric outflow (or sometimes asymmetric outflow depending on the given situation at hand) being quite powerful towards the surface of the Earth. Thus, this just goes to show that even the more interesting and curious details of a larger weather event can be quite interesting to understand on a more profound level.
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© 2018 Meteorologist Jordan Rabinowitz