CAASPP Success - Grade 4 Reading Comprehension - Expository #2

Understanding Hurricanes

How Hurricanes Form

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[1] Hurricanes are some of the most powerful and complex storms on Earth. They originate over warm ocean waters, typically in tropical regions, where the sea surface temperature is at least 80°F (26.5°C). The formation begins with a cluster of thunderstorms, known as a tropical disturbance. For a hurricane to develop, several critical factors must come together: warm water, low air pressure, and favorable wind patterns.

[2] Warm ocean water is the primary fuel for a hurricane. As the warm water heats the air above it, the air rises, creating a low-pressure area below. This rising warm air starts to spiral due to the Earth's rotation—a phenomenon known as the Coriolis effect. As the system draws in more warm, moist air, the storm begins to strengthen. If the wind speeds within the storm reach 39 mph, it becomes a tropical storm and receives a name. When the wind speeds exceed 74 mph, the storm officially becomes a hurricane.

The Structure of a Hurricane

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[3] A hurricane has a well-defined structure with several key features. At the center is the eye, a calm area where the skies are often clear, and winds are light. Surrounding the eye is the eyewall, where the storm's most powerful winds and heaviest rains occur. Extending outward from the eyewall are rain bands, spiraling bands of thunderstorms that can stretch for hundreds of miles, contributing to the storm’s size and intensity.

How Hurricanes Are Tracked

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[4] Tracking hurricanes is essential for predicting their path and potential impact. Meteorologists use various tools to monitor hurricanes, including satellites, which provide images of the storm from space, and specially equipped aircraft that fly into the hurricane to measure wind speed, temperature, and pressure. These data are fed into computer models to predict the storm's future path and strength.

[5] Despite advances in technology, forecasting hurricanes remains challenging. While predictions of a storm's track have improved significantly, accurately forecasting its intensity is more difficult. This is because intensity depends on a complex interplay of atmospheric and oceanic conditions, including sea surface temperature, wind shear, and moisture levels. Models used to predict hurricanes often show different possible tracks and intensities, and meteorologists must analyze these models carefully to provide the most accurate forecasts.

The Impact of Hurricanes

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[6] Hurricanes can have devastating effects when they make landfall. The combination of high winds, heavy rainfall, and storm surges can cause widespread destruction. Storm surges, which occur when strong winds push seawater onto land, are particularly dangerous and can lead to severe flooding in coastal areas. The Saffir-Simpson Hurricane Wind Scale is used to classify hurricanes into five categories based on their wind speeds, with Category 5 hurricanes being the most destructive, capable of leveling buildings and causing catastrophic damage.

Hurricane Preparedness and Response

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[7] Understanding how hurricanes form and how they are tracked is crucial for preparing and responding to these powerful storms. Accurate forecasts allow communities to take necessary precautions, such as securing homes, evacuating vulnerable areas, and preparing emergency supplies. The better prepared a community is, the more effectively it can respond to the challenges posed by a hurricane, reducing the risk of loss of life and property.

[8] Hurricanes are a powerful reminder of nature's force, but with knowledge and preparation, we can minimize their impact. By understanding the science behind hurricanes and the methods used to track them, people can stay safer during hurricane season and better protect their communities.

“Warm ocean water is the primary fuel for a hurricane. As the warm water heats the air above it, the air rises, creating a low-pressure area below. This rising warm air starts to spiral due to the Earth's rotation—a phenomenon known as the Coriolis effect. As the system draws in more warm, moist air, the storm begins to strengthen. If the wind speeds within the storm reach 39 mph, it becomes a tropical storm and receives a name. When the wind speeds exceed 74 mph, the storm officially becomes a hurricane.”