A hurricane is a powerful storm that measures several hundred miles in diameter. Hurricanes have two main parts. The first is the eye of the hurricane, which is a calm area in the center of the storm. Usually, the eye of a hurricane measures about 20 miles in diameter, and has very few clouds. The second part is the wall of clouds that surrounds the calm eye. This is where the hurricane’s strongest winds and heaviest rain occur.
Inside a Hurricane
Hurricanes are born over warm, tropical oceans. Hurricanes are fueled by water vapor that is pushed up from the warm ocean surface, so they can last longer and sometimes move much further over water than over land. The combination of heat and moisture, along with the right wind conditions, can create a new hurricane.
Understanding a Radar Image
The colors in hurricane radar images indicate the amount and size of rain falling in a given area (see above, right). Each raindrop reflects the energy from the radar. Therefore, the more raindrops in a certain area, or the larger the drops, the brighter the color in the radar image of that area. Composition also has a strong effect; ice covered with liquid water gives the strongest reflection. The radar image above is really measuring the amount of moisture in the air. The bright red color around the eye indicates the area of heaviest rainfall. The green colored area has a moderate amount of rain, while the blue areas represent the least amount of rain.