Hurricanes are large, dangerous storms that come from the tropical oceans. Hurricanes happen in many oceans around the world, where they might also be called cyclones or typhoons. Hurricanes need warm water to start, annd grow. If they move onto land they slowly weaken and then die. Many fade over water, without hitting land. Most hurricanes start in the summer and fall, when the sun is high in the sky. Oceans get very warm from the sunlight- over 80 degrees. The warm water evaporates and makes clouds and then thunderstorms. If thunderstorms form and stay together for a few days, they might start to slowly rotate as a group. Instead of the weather being calm, it becomes disturbed, so we call this a tropical disturbance.
Warm, humid air rising into the thunderstorms keeps them going and slowly spinning around each other. When air rises into the sky, there's less of it left near the ground or water, so the air pressure lowers. If the pressure gets lower and the group of thunderstorms still rotates together, we call it a tropical depression. Tropical depressions are given numbers to help keep track of them. If a tropical depression gets stronger, with winds faster than 39 mph, we call it a tropical storm, and it is given a name. Tropical storms have more rising air and lower pressure. They make lots of rain and sometimes they cause floods. The more they grow, the lower the pressure falls, and the stronger the winds blow.
When the winds in a tropical storm reach 74mph, it becomes a hurricane. Hurricanes are made of a whole lot of thunderstorms spinning together as one large group. They make high winds and extreme rain. Once a hurricane starts, it can keep itself going as long as it has warm water to feed it, and as long as the winds just outside the hurricane are not too strong. Powerful hurricanes have eyes, or no clouds right in the middle of the storm. That happens from the spin of a hurricane moving air outward, above the ocean or land, with warm, dry air sinking in the middle of the storm. In the eye of the storm the weather is often calm, dry, and mostly clear! Even though hurricanes are big, they don't move very fast. Hurricanes and tropical storms can last for more than a week as they slowly cross the oceans. We track them on a satellite. This gives people time to prepare and time to get out of the way of danger. We give hurricanes and tropical storms names to make it easier to tell them apart because sometimes you can have several in the ocean at the same time. For the Atlantic Ocean, and eastern Pacific Ocean, the names are alphabetical, and they alternate male and female.
We've learned a lot from scientists who fly in special airplanes into the storms to take measurements. In the United States these people are called hurricane hunters. They have a dangerous job but it's important. They collect data to learn more about tropical storms and hurricanes so that we can have better predictions to help us be safer.
All hurricane winds make ocean waves higher. When hurricanes get close to the coast they send large waves onto land, called storm surge, that builds up the water level. The storm surge surprises many people because it happens fast. People who are on or near the beaches can drown in the storm surge. As hurricanes get close to land, weather forecasters use radar to see the rain and wind pattern inside of the clouds. Large or slow tropical storms and hurricanes can leave feet of rainfall, even far inland, away from the ocean. Some floods happen around rivers, but they also happen near low spots on the ground. Floods from hurricanes may take a long time to go away. Floods also make snakes and wild animals leave their homes, so you have to be careful.
Hurricane winds pick things up, blow them around, and cause damage. They can last many, many hours when the storms move slowly. You can use the wind of a hurricane to tell how strong it is and put it into a group or category. Category one hurricanes have winds between 74mph and 95mph. The higher the category, the stronger the wind. Category five hurricanes have wind over 156mph. These are the strongest hurricanes, and they cause disasters if they strike.
Hurricanes are more than wind and rain and storm surge. Thunderstorms in a hurricane have lightning and they can make tornadoes. Winds from any hurricane damage homes, trees, power lines and anything else outside, especially weak homes and mobile homes that are on blocks. The wind in a hurricane can turn over mobile homes or push trees on top of them. Things falling or flying through the air can even go through the side of a home. It’s important to listen to instructions when hurricanes get close so that you can stay out of danger.
A Hurricane Watch means that a hurricane might strike in less than two days. Plan what to do if the hurricane keeps coming. In a Hurricane Watch, clean up all the things around your yard that might be picked up by wind, or carried away in a flood. Double check your hurricane disaster safety kit. Inside of it would be things your family would need in case you lose electricity or have to leave your home. Food, water, blankets, and a first-aid kit are important. Other things you want to have are flashlights, medicine, a weather radio, important phone numbers, and money. Be sure there is gas in the car, and decide on whether you should board up windows to keep the glass from breaking.
A Hurricane Warning means the hurricane is going to strike or come very close to you. Take action. Many times, you can stay in your home if you are not too close to the water and if the building is strong. Find shelter in the middle of the building in a hallway or small room without windows. Get under something strong like stairs. Some houses have a special room for hurricane shelter called a saferoom.
Your city may tell people that they have to leave their homes and go to a hurricane shelter, or drive away from the coastline or flood zone. This is called evacuation. An evacuation is to keep you from being in a dangerous place. If you stay behind and have an emergency, no one might be able to get to you to help. After a hurricane you might not have electricity for a few days and that makes it hard for people to live and be comfortable. In the worst hurricanes, homes are destroyed. People may not have clean water or electricity for many weeks, so they cannot stay in their homes.
For all the bad things that hurricanes and tropical storms do, they actually help the Earth. They are a large part of the water cycle, transporting moisture, cleaning air, and even removing old tree growth.