At-home STEM activity: Why is there a hurricane season?
This week, we’re learning all about seasons!
If you live near the Atlantic coast in North America, then you know that summer is both a lovely time to spend by the shore and holds the possibility for some dangerous storms. In the North Atlantic, hurricane season is June 1 through November 30, with activity peaking between August and October. Nearly all tropical storms in the Atlantic area occur during this window, which very nearly lines up with the summer season (June 20-September 22). So why is that? The answer has to do with both wind and water.
The way a hurricane forms isn’t much different from how a normal rain storm is created. Water evaporates out of the ocean, condenses into a cloud, and when the cloud gets to heavy, creates rain (precipitation). What sets a hurricane apart from a regular rain storm is the amount of water and high wind speeds, and this is where summer comes in.
In the summer, the Sun’s light is hitting the Earth more intensely. This warms up the oceans causing greater amount of water to evaporate. Once all that water vapor is in the air, winds push it higher into the sky until the vapor cools and condenses into clouds. So now we have a big rain cloud, but what about the wind?
One measurable quantity of wind is how much it changes direction in a short distance. This is called wind shear. A strong wind shear means that the direction of wind changes a lot, and that frequent changing of wind direction helps prevent storms from intensifying. In the summer, wind shear greatly decreases, reaching a minimum in August, so the wind is blowing in the same direction for a long time. When this wind meets the big rain clouds, it starts pushing them. And thus, we have a hurricane.
Image via NASA
The wind keeps pushing the clouds in the same direction, and the storm forms its familiar spiral shape. It spins around, feeding itself while it remains over the ocean—the rain from the storm lands back in the ocean, evaporates back in the air, condenses into the storm clouds, and repeats the process. Once the storm reaches land, though, it usually loses some speed, since it doesn’t have the constant fuel from the ocean water to keep it going.
To sum this all up, the combination of warm water and minimal change in wind direction is literally the formula for a perfect storm. So if warm ocean water causes hurricanes and tropical storms, you may be wondering what will happen as the oceans get warmer?
You might think that warmer oceans would lead to more hurricanes, but according to the Global Warming and Hurricane research done by the NOAA’s Geophysical Fluid Dynamics Laboratory, there isn’t significant evidence that there will be a greater number of tropical storms and hurricanes as ocean temperatures increase. But, unfortunately, that’s not all the scientists found. While there probably won’t be more hurricanes, the normal amount of storms that occur will most likely include more intense storms. According to a model with a 2°C increase in ocean temperatures, the research concludes that rainfall, storm size, and global proportion of storms rated very intense (category 4 and 5) will likely increase.
It can be a little overwhelming and scary to think about the effects of climate change, but remember that with our own actions, we can help mitigate those effects. Little things you can do at home—recycling, reducing water use by turning off the faucet when you brush your teeth or taking a shorter shower, and turning off lights and electronics when you don’t need them on, to name a few—can help make a difference, and maybe help reduce those big, intense hurricanes in the future.
Now that we know one way that the seasons effect weather on Earth, let’s model what that weather looks like by making a hurricane in a jar.
Hurricane in a Jar
Materials:
Glass jar
Liquid soap that contains Glycol Stearate (it should be an opaque soap, not clear)
Water
Food coloring (optional)
Instructions:
Fill your jar approximately 1/4 to 1/3 of the way full with soap.
Fill the remaining space in the jar with water. As the water gets to the top, overfill the jar a little to get rid of any soap bubbles.
If you want your hurricane to have color, add a couple of drops of food coloring. Add blue food coloring to look like a storm on Earth, or red to look like Jupiter’s big red spot. The spot on Jupiter is similar to a hurricane, but instead of swirling water, the storm is made of ammonia. The same spot has been observed since 1878!
Tightly screw on the top of the jar, give it a shake, and watch as it appears you’ve captured a storm in a bottle!
Activity from onetimethrough.com
When you’re all done watching the clouds swirl around the jar, (as long as you didn’t use too much food coloring) you can keep your hurricane in a jar next to your sink and use the storm to wash your hands!
