Part 6 of our Hurricane Smart Kids series.

Here is something amazing: the hurricane that might threaten your coastline in September probably started as a tiny blip in the atmosphere off the coast of West Africa weeks earlier. That blip is called a tropical wave.

Step 1: The Sahara Desert Starts It All

The Sahara Desert heats up intensely under the African sun. Meanwhile, the Gulf of Guinea — the ocean to the south — stays cooler. That temperature difference creates waves of energy in the atmosphere called African Easterly Waves. These waves roll off the African coast every few days during summer and early fall — like a parade of invisible ripples heading west across the Atlantic.

Step 2: Finding Warm Water

As the wave moves westward over the Atlantic Ocean, when the ocean water is at least 80 degrees Fahrenheit, the warm water heats the air just above the ocean surface. That warm, moist air rises. As the air rises, the water vapor condenses into clouds and rain. This releases heat energy — and that heat energy makes more warm air rise, which makes more clouds... It's a loop. And if conditions are just right, that loop gets bigger and bigger.

Step 3: Earth Gives It a Spin

As all that warm air rushes inward and rises, the Earth's rotation deflects it — it curves. In the Northern Hemisphere, this deflection causes the air to spin counterclockwise. This is called the Coriolis effect, and it is what gives a hurricane its spin.

Step 4: The Storm Organizes

  • Tropical Disturbance: Just a cluster of thunderstorms — no real center yet
  • Tropical Depression: A spinning center forms. Winds reach up to 38 mph.
  • Tropical Storm: Winds reach 39–73 mph. It gets a name!
  • Hurricane: Winds hit 74 mph or higher. The eye appears. The storm is fully born.

Step 5: What Stops It From Growing?

Most tropical waves never become hurricanes. Wind shear rips the storm apart. Dry air from the Saharan Desert can suffocate it. Cool water removes its fuel source. Only when the wave avoids all of these obstacles does it grow into a full hurricane.

You can follow tropical wave activity yourself during hurricane season on our Live Storm Tracker! Also read our adult version: How a Hurricane Forms.

For parents and educators: This article pairs well with a map activity — have students trace a typical Cape Verde hurricane track from the African coast to the Caribbean or US.