High Resolution images can be found by clicking here.
Caption for Item 1: TAKE WARM WATER, STIR
What makes a hurricane? First, warm water - at least 82 degrees, in fact. Several weeks after the Sun shines brightest on the tropics in late June in the northern hemisphere, the waters reach their warmest. Here, orange and red indicate the necessary 82-degree and warmer water, sea surface temperatures (SSTs) taken by the Advanced Microwave Scanning Radiometer-EOS (AMSR/E) aboard the Aqua satellite from beginning in June 2002. Next, add a disturbance, generally easterly waves off of Africa, formed from winds resulting from the clash between the hot Sahara Desert and the cooler Gulf of Guinea. These waves provide the initial energy and spin required for a hurricane to develop, as imaged by the Geostationary Operational Environmental Satellite (GOES, operated by NOAA) on Sept. 1-15, 2001. Credit: NASA
Caption for Item 2: MIX THOROUGHLY, BAKE
With the right mix of winds and SSTs, an ordinary cluster of tropical thunderstorms can explode into a tropical storm. Winds converge, forming the familiar circular pattern of clouds. Warm, rising air in the storms draws water vapor up from the ocean. The vapor condenses in clouds and releases heat, warming the eye, evaporating more surface water and feeding the hurricane's heat engine, continuing the cycle.
Data from Hurricane Erin, Sept. 10 - 15, 2001.
a) wind speed/direction, from Seawinds instrument on QuikScat satellite [NASA]
b) cloud structure, from Visible and Infrared Scanner (VIRS) on the Tropical Rainfall Measuring Mission (TRMM) satellite [NASA/NASDA]
c) rainfall rates (green, in excess of 2 inches per hour), Microwave Imager (TMI) and Precipitation Radar (PR) on TRMM [NASA/NASDA]
d) eye warmth (red), Convection And Moisture EXperiment (CAMEX) [NASA]
e) GOES [NASA/NOAA]
Caption for Item 3: HURRICANE HEAT ENGINE
Hurricanes essentially act as engines, drawing energy up from warm tropical ocean waters to power the intense winds, powerful thunderstorms, and immense ocean surges. Water vapor from the warm ocean surface evaporates, forming towering convective clouds that surround the eyewall and rainband regions of the storm. As the water vapor cools and condenses from a gas back to a liquid state it releases latent heat. The released heat warms the surrounding air, making it lighter and promoting more clouds. Because the hurricane-speed winds surrounding the clear eye are often absent from the center of a hurricane, the heaviest rain clouds are pushed out to form a ring around the center, leaving a relatively fair-weather eye. Credit: NASA
Caption for Item 4: MODEL HURRICANE
By synthesizing data from multiple instruments and satellites, scientists get a full picture of the many ingredients of a hurricane. Satellites that monitor Earth day-to-day give pictures of both normal and unusual terrestrial, oceanic, and atmospheric activity. Scientists then build physical and computer models of the interactions and activity, which they can study to find patterns and ultimately make predictions. Scientists can use these models to make better predictions of severe weather patterns. Credit: NASA
Caption for Item 5: AIRS INSTRUMENT ON AQUA SEES PONGSONA
The Atmospheric Infrared Sounder experiment on NASA's Aqua spacecraft reveals important new information to supplement the familiar overhead views of hurricanes (called typhoons in the Western Pacific) that come from satellites. Here AIRS shows some of the internal temperature structure of Supertyphoon Pongsona just as it hit the island of Guam on December 8, 2002. Each of the colored surfaces represents a particular temperature, from red and warm near the surface to yellow and very cold near the top. Normally, these so-called isotherms would be much smoother and nearly horizontal. Here we see how the latent heat released in convective updrafts causes the isotherms to bulge upward. This bulging is even seen more than 50,000 feet above sea level. This relatively warm air cap above a hurricane has rarely been observed and can only be measured with an instrument like AIRS. As we zoom in on the lower 30,000 feet, the temperature structure becomes more striking. It is
even possible to discern a dip in the center at the lowest level, where cooler and drier air descends and forms the often cloud-free eye of a hurricane.Credit: NASA