Answer:
(1) Hurricanes are the largest and most violent storms on Earth. They are large rotating storms with high speeds that form over warm waters. These storms are known as hurricanes in North America and the Caribbean. However, they have different names in other regions. In South East Asia, they are called typhoons. In the Indian Ocean, they are known as cyclones. Hurricane winds move at the speed of at least 74 miles per hour. They can be as wide as 300 miles. But, how are these huge storms formed?
a world map showing that hurricanes occur north of the equator in the Atlantic Ocean, cyclones occur north and south of the equator in the Indian Ocean, and typhoons occur north of the equator in South East asia
(2) Hurricanes are often compared to engines. Just like engines they need a type of fuel. Hurricanes form over warm ocean waters near the equator. For hurricanes, their fuel is warm, moist air. When hurricanes form, the warm, moist air above the ocean rises upward from close to the surface of the water. Because the warm air rises, it results in less air under the surface of the water. This area with less air is known as an area with low pressure.
(3) Air from areas surrounding this low pressure space pushes in to the area. This fills the low pressure area. The new air in this space becomes warm and moist and also rises. As the air continues to rise, the air surrounding the space swirls in to take its place. This process of air swirling in to replace air that has risen continues. Eventually, the moisture in the air forms clouds.
(4) The wind and the clouds that form create a system. A system is a pattern of weather. The system of clouds and winds continues to spin and grow. The water evaporating from the ocean's warm surface acts as the fuel, which is what helps this spinning and growing. The system rotates faster and faster until the eye of the storm forms in the center area. Ironically, the eye of the storm is the calmest part, and it has very low air pressure. The higher pressure above the hurricane continually flows down into the eye.
a view of a hurricane from space with the eye of the hurricane visible in the center of the hurricane
© iStock 2015
(5) Outside of the eye of the hurricane, is the eye wall. This is where the most dangerous winds are found. Further outside that are the rain bands. The rain bands are a group of thick clouds. These clouds create the unique look of the hurricane. Hurricanes start out as tropical storms. They are known as hurricanes once their winds reach 74 miles per hour. The speed of the wind determines the category. Category 1 hurricanes have wind speeds of 74-96 miles per hour. Category 5 hurricanes move at 157 miles per hour or higher.
(6) Once hurricanes hit land, their speed lowers. This is because they are no longer being given energy, or fuel, from the warm ocean waters. As hurricanes move inland, they bring heavy rains and cause wind damage. The amount of rain and wind damage depends on the size and speed of the hurricane. Hurricanes can reach over 300 miles in width.
(7) While hurricanes are known as typhoons and cyclones in different parts of the world, they are all the same type of storm. These tropical cyclones all form the same way. They form above warm ocean waters near the equator and use warm, moist air as fuel. This fuel allows them to continue to grow and rotate at faster speeds until they hit land. Once they hit land, they usually slow down because they no longer have the warm, moist air to fuel them. Although they slow down, they still move at speeds that allow them to cause great damage.
(8) Hurricane Irma is a recent storm that touched down in the United States, forming from a tropical wave in the Atlantic Ocean. This wave lead to rain showers and thunderstorms, and eventually, the showers and thunderstorms became organized into a system. This created a low pressure area, allowing a hurricane to form. Hurricane Irma continued to grow as it moved across the ocean. By the time it hit the Caribbean, it was a Category 4 hurricane. It continued to change in size and speed. Finally, it touched down in Florida as a Category 4 hurricane before gradually weakening in power and dying in Missouri.
an image showing the damage that Hurricane Irma made in Florida
© Cleverguy122 2017
Creative Commons, ShareAlike 4.0
(9) Hurricanes are a severe weather occurrence. Some hurricanes stay small, while others become more powerful until they touch down on land and start to lose power. However, hurricanes can still be catastrophic once they make landfall. Because scientists have learned so much about how hurricanes form, they are able to monitor them and warn people to take precautions if a hurricane hits in their area.
How does the cause and effect text structure in paragraphs 2 to 4 help the reader understand how hurricanes are formed?