You might have heard about hurricanes and typhoons before, violent storms that form over the oceans in the tropics and cause large rainfall and strong winds. When these storms reach land, they often cause widespread destruction.

Hurricanes always form over the ocean because they feed off the energy from warm ocean water. Compared to soil, water has a high heat capacity, meaning that it can store more energy per unit. In the tropics, where the angle of the sun is very small, the sun heats up the ocean surface particularly strongly. That’s why ocean temperatures in the tropics are much warmer than in the UK.

In warm water, some molecules will gather enough energy to evaporate. As a result, some ocean water will rise in the atmosphere as water vapour. Higher up, the atmosphere is colder and the water will condense again as raindrops — but in this process the water will also release latent heat which provides the storm with more energy to intensify into a huge storm.

Predicting where exactly hurricanes will form remains a huge challenge for weather forecasters. By learning more about the physics of these storms, we can help improve forecasts and give people in affected areas time to get to safety.

Bonus fact: What is the difference between typhoons and hurricanes? They are basically the same! “Hurricane” is the word we use for storms in the Atlantic Ocean, storms in the Pacific are called “typhoons”. More generally we speak of tropical cyclones.
 

Shirin Ermis
Graduate Student,
University of Oxford