The word hurricane is from the Spanish word Huracan’ which means “great wind”. You may have heard the words typhoon and cyclone used to describe big storms. Each of these words (hurricane, cyclone, and typhoon) is used to describe a powerful, tropical storm.
If you live in a hurricane-prone area or have lived through a hurricane, like we have located in NC, you already know how powerful hurricanes are and the extent of damage and destruction they cause.
I compiled this hurricane information and hurricane lesson as a way to help our kids understand what they were, especially since we have experience quite a few.
If you’re looking for other weather related activities, check out these weather related activities – make a thermometer, make an anemometer, make a rain gauge, and track rainfall on our rainfall chart.
Table of Contents
What is a Hurricane?
Hurricane is used to describe these tropical storms in the North Atlantic Ocean, north Pacific Ocean, and South Pacific Ocean closer to the United States. Typhoon is used to describe these storms in the North Pacific Ocean closer to Japan. Cyclone describes these large storms in the Indian Ocean and in the South Pacific Ocean around Australia.
Where do hurricanes form?
Hurricanes are very large and powerful storms that form where the climate is hot. They form mostly in “the tropics” – areas around 20 º north and 20 º south of the equator, where the water temperature is at least 80º Fahrenheit.
Below is a satellite photograph of Hurricane Katrina that hit the United States in August 2005. While it was not the most powerful hurricane to hit the United States, it is the most costliest to date. The storm looks like a large swirling cloud. When the winds in these tropical storms reach 74 miles per hour, the storm is called a hurricane.
What is the average size of a hurricane and how fast do they move?
A hurricane can be hundreds of miles across. The average size is 300 miles. Use a map to measure 300 miles from your house. How long would it take you to drive 300 miles? Even though hurricanes are extremely powerful, they are slow movers and don’t always move in a straight line. Hurricanes move at about 10 to 20 miles per hour.
To understand how a hurricane forms, let’s do a little activity so your children can see how warm and cold molecules move differently. Hot and cold air is key to the formation of a hurricane.
How Do Hurricanes Form?
How Hurricanes Form
- 1 1 cup measuring cup
- 2 glass containers mason jars work well (the dollar store has these)
- Red and blue food coloring
- 1 Drinking straw
- 1 Flashlight
- 1 bowl of ice water
- Cut the straw to a 5" length, set aside
- Measure 1 cup of cold tap water and put it into one of the jars. Place it into the bowl of ice to cool it further. Set aside for about 15 minutes.
- Place 1 cup of water into the microwave and heat for 3 minutes or until it boils. Then, pour this into one of the jars and immediately cover to help retain the heat.
- Place 1 cup of water into the microwave and heat for 3 minutes or until it boils.
- Gather the jar of cold water, the jar of hot water, the blue food coloring, and the red food coloring.
- Next, you'll add red food coloring to the hot water and blue food coloring to the cold water. However, have your children do this methodically, so they see how the food coloring behaves in cold water vs. hot water. Add one drop of blue food coloring into the cold water, and watch what happens. Next, add one drop of red food coloring to the hot water. If you can, do the drops simultaneously, so your students can see how the food coloring moves through cold water versus hot water. (An explanation of what is happening is listed below.)
- Now, quickly set up this next step. Now, you will have 1 cup of cold water colored blue, 1 cup of hot water colored red, and 1 cup of clear hot water.
- Turn on the flashlight and place it behind the clear cup of water so it shines through the cup and you can see the red and blue water as you begin to drop the colored water into the hot water.
- Next, you will drop 1 drop of the blue water into the 1 cup of clear, hot water. To do this, place the straw in the cold water and place your finger over the top of the straw. Difference in air pressure between the inside and outside of the straw will cause some of the blue water to rise into the straw.
- Keeping your finger over the top of the straw, move the straw 1/8” down into the clear water. Slowly move your finger so 1 drop of the blue water goes into the clear water. Watch the drop of blue? Where did it go? Notice how it moves through the hot water to the bottom.
- Then, do the same procedure with the red water into the clear water. What happens to the red water when it is dropped into the clear, hot water?
What happened in step 6 above? In the video above, you can see what happened when the room temperature food coloring was put into cold water vs. hot water. When the food coloring was in hot water, the water molecules move more quickly and have greater kinetic energy than in cold water. This increased energy causes the water molecules to move apart from one another more rapidly, which increases the space available for the food coloring molecules to move into. As a result, the food coloring molecules are able to spread more quickly through the water in hot water than in cold water.
What is Happening In Steps 9, 10, and 11
The (blue) cold water drops through the hot water to the bottom and the hot water stays near the top. Air does the same thing. Notice how the blue water goes down to the bottom of the warm water and then dissipates. But the cold (red) water, drops down, but then travels back up to the top.
The warm air in a storm moves to the top and the cold air remains at the bottom. The rising of warm air and the movement of cold air into its place is called convection. Storms then form out of the strong, warm air.
How Hurricanes Form
Once the warm air rises and the cool air rushes in, winds form. Remember, the Earth is always spinning. The rushing winds in these storms begin to move in a spiral as they respond to the spinning of the Earth. But what’s interesting is the direction in which the clouds spiral.
In the photograph above you can see the spiral form of the clouds. Hurricane Andrew was in the Northern Hemisphere where hurricane clouds rotate (or spin) counterclockwise. In the Southern Hemisphere, hurricane clouds rotate clockwise (in the direction a clock moves).
Teacher note: This difference in rotation direction is due to the Coriolis force. This is a great research project for your older students.
Once these rotating winds reach 74 miles per hour, a hurricane is formed. The heavy rains may also have thunder and lightning.
So, hurricanes need 3 ingredients to form:
1. Ocean water that is at least 80º F.
2. Air above the Earth filled with moisture.
3. Winds moving at a high speed in the same direction above the Earth.
How Does the Hurricane Storm Surge Form?
Which of the following do you think causes the most damage during a hurricane and is the deadliest part of a hurricane?
- A. Strong winds
- B. The storm surge-ocean water levels that can rise 10 to 20 feet higher than normal tide
- C. Heavy rains and flooding
The answer is B. The storm surge is the most dangerous part of a hurricane. However, strong winds and flooding are extremely dangerous. The storm surge is not a giant wave. Storm surge is the rapidly rising level of the sea level. Storm surges in hurricanes have raised the sea level as high as 20 feet above normal sea level. That is as high as a 2 story building! It can happen quickly and catch people off guard.
To understand the formation of the storm surge, let’s discuss air pressure. Air is always pressing down on us. It is hard to feel the air between the surface of the Earth and space pressing down on us, but it is! Look at the drawing below. In a hurricane, the warm air is quickly moving up and it takes weight off of whatever is below it. So, instead of a high pressure pressing down on us, there is lower pressure. This area of lower pressure in the hurricane is surrounded by higher pressure on the outside of the hurricane. This caused a dome of water to rise in the hurricane (where the lower pressure is located). This dome of water is the rising sea level—the storm surge.
Learning About Hurricanes Activity: Creating a Dome of Water
Let’s do an easy activity that demonstrates how a dome of water forms.
Creating a Dome of Water
- 1 glass bowl The top of the bowl should be small enough to be covered by a single piece of plastic food wrap.
- Packing tape
- Water at room temperature
- 12" piece of fishing line
- Fill the mixing bowl 3/4 full of water. Let is sit and reach room temperature.
- Cut a piece of plastic wrap that is large enough to sit on top of the surface of the water, cover all sides of the bowl, and drape over the sides of the bowl. The goal is to have the plastic wrap serve as a seal on the surface of the water and the sides of the bowl. You should have enough plastic wrap to press against the sides of the bowl and up over the rim. Again, the plastic wrap could form a thin covering directly on the surface of the water without any air pockets. The wrap should also be directly against the sides of the glass bowl and over the rim to make a tight seal. You might need to seal the plastic wrap with packing tape around the sides of the bowl.
- Using a several pieces of packing tape, tape the fishing line in the center of the water/plastic wrap. You are going to want to pull up GENTLY.
- Slowly pull up on the fishing line. You will see the plastic wrap rise and the water come up with it. This simulates the dome of water that forms in a hurricane. However, the dome (or storm surge) is a much larger area.
What is happening.
Before you pulled up on the fishing line, the air pressure across the entire surface of the water and plastic wrap was the same. However, as you pulled up on the fishing wire (to simulate the rising warm air in a hurricane), the pressure on the surface of the water right under the fishing line became lower (the air pressure was pulling up at this point). However, the pressure around the edges of the water remained higher than the pressure right at the center, causing the water under the fishing line to rise up. This area of rising water simulates the storm surge in a hurricane.