What you need:
- A medium to large bowl
- Spoon or something to stir with
- Food coloring
- Fill your bowl about 2/3 the way full with water
- Stir the water in the same direction
- Keep stirring until the water is moving fast enough to keep going around the bowl by itself
- Add 1-2 drops of food coloring
- Watch how the color spreads and circulates
The science/how this applies to hurricanes:
The Atlantic Hurricane Season (covering areas in the Atlantic Ocean, Gulf of Mexico and Caribbean Sea) runs from June 1- November 30. While hurricanes can still happen outside of this range, this is when the majority of hurricanes and tropical storms will occur.
A hurricane starts out as an area of low pressure. Low pressure systems move counterclockwise in the Norther Hemisphere, and clockwise in the southern Hemisphere. We represent that by stirring the water around in the bowl.
Just like general thunderstorms, hurricanes continue to grow with the key ingredients of lift, instability and moisture, which are abundant over warm ocean waters. Warm air rises, and as it rises it creates more instability in our atmosphere. The ocean creates the perfect place for hurricanes to grow because ocean waters are warmest by the end of the summer and provide an abundant source of moisture, or water, to keep storms growing.
As storms grow and the area of low pressure deepens, and wind speeds pick up. Once the storm has 39-73 mph sustained winds it is classified as a tropical storm and gets a name to help identify it. If winds pick up to 74 mph or higher, it becomes a hurricane.
While we won’t be stirring the water that fast, getting the water to the point where it can continue to swirl in a circle in the bowl by itself will do the trick for this experiment!
We added the food coloring to get an idea about what else is going on with the spin created by a tropical storm or hurricane.
The center of the spinning represents the “eye” of the hurricane. While the eye is actually the calmest part of the storm, the outer edge, or “eyewall” is where some of the strongest circulation and most damaging winds are found.
Notice how the color spreads out and creates bands around the middle part of the circulation. These are called rainbands.
Rainbands are curved bands of clouds and thunderstorms that continue to feed off of the moisture and instability available as they spiral away from the eyewall. The storms within these bands are usually strong to severe and are capable of producing heavy rain, wind and even tornadoes. While there can be gaps between these bands of strong storms, they are the first part of the hurricane to make landfall.
Notice that even if you drop food coloring into the center of the bowl of spinning water that the water spreads to the outer edge. Unlike a thunderstorm that will ofter be smaller than your neighborhood, hurricanes are large systems often the size of several states as they spin over warm water.
A hurricane’s doesn’t always correlate with its intensity. Hurricanes are rated on the Saffir-Simpson Hurricane Wind Scale on a scale of Category 1-5 based on sustained wind speed.