Atlantic Hurricanes With Dr. Jeff Halverson: Understanding the 21st Century's New Threat
| 16. Factors that Lead to Hurricane Intensification | |
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Why did Hurricane Isabel - a powerful 2003 Atlantic hurricane - remain a Category 5 for as long as 3 consecutive days? This is nearly unprecedented. Much of this has to do with the very warm ocean water that Isabel encountered, and complete lack of destructive winds high in the atmosphere. + View video + Download Quick Time |
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Media Content: The TRMM radar showed that in the early stages of Isabel, the African Wave was generating impressively tall thunderstorm clouds. Towering high into the troposphere, they are called Chimney Clouds. Inside these clouds, the rain is very intense. When water vapor condenses into rain, it releases heat energy into the surrounding atmosphere. The release of heat leads to warming inside the storm core…a prerequisite for a hurricane eye to develop. + Download media Several other favorable conditions conspired to intensify Isabel into a Cat 5 monster. First, the ocean surface temperatures across the tropical Atlantic were very warm. The warm water that freely evaporates into the atmosphere provides the raw fuel for the hurricane engine. + Download media National Standards: E.2, K-4: students should develop understanding about science and technology. D.1, 5-8; students should develop an understanding of structure of the earth system. D.1, 9-12; students should develop an understanding of energy in the earth system. |
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| 17. Sea Surface Temperature | |
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One of the amazing properties of water on Earth is that water has the highest heat capacity of just about any natural substance known. It takes months for the Atlantic waters to absorb the intense tropical sunlight, but during the process an amazing amount of energy is stored in the water. This energy makes its way into tropical storm clouds when water evaporates from the ocean surface. Water molecules are in essence "mobile solar collectors" that transfer the ocean's energy into clouds, where the energy can then power a hurricane.
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Media Content: The sequence of dramatic images portrays how the Atlantic steadily warms over the course of weeks and months. Satellites now enable us to track the warming and cooling of vast ocean areas. They measure what is called the "skin temperature" of the ocean - the very uppermost one-millimeter - using microwave energy. + Download media National Standards: E.2, K-4: students should develop understanding about science and technology. D.1, 5-8; students should develop an understanding of structure of the earth system. D.1, 9-12; students should develop an understanding of energy in the earth system. |
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| 18. Thermoclines - Reservoirs of Heat | |
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Hurricane forecasters must consider not just the temperature of the ocean's skin (the sea surface temperature), but also the depth of warm water - called the thermocline. Water vapor evaporated from oceans is a hurricane's primary fuel. If the ocean temperature is a measure of the fuel's octane rating, the depth of the thermocline is the measure of the size of the fuel tank. + View video + Download Quick Time |
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Media Content: Not only is the skin temperature of the ocean water important, but also how deep the warm water extends. Very deep layers of warm water resist the tendency of a hurricane to stir up cold water from the ocean deep. The cold water means a lower octane rating of the fuel, and the hurricane engine will run much more slowly. + Download media National Standards: E.2, K-4: students should develop understanding about science and technology. D.1, 5-8; students should develop an understanding of structure of the earth system. D.1, 9-12; students should develop an understanding of energy in the earth system. |
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| 19. Question and Answer | |
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| 20. Under the Hood | |
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Trying to understand the physics of a hurricane’s structure may seem intimidating, but using the analogy between a hurricane and the engine of a car make the subject much easier to relate to. + Read more / View video + Download Quick Time |
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National Standards: D.1, 5-8; students should develop an understanding of structure of the earth system. D.1, 9-12; students should develop an understanding of energy in the earth system. |
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