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Which Factor Controls the Water Cycle? — Reading Comprehension

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MS-ESS2-6

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This NGSS-aligned science reading passage explores the question: Which factor controls the water cycle? Students will learn that the Sun is the driving force behind the continuous movement of water through evaporation, condensation, precipitation, and collection. The passage uses clear language suitable for middle school readers and includes scientific vocabulary such as transpiration, atmosphere, and climate. Real-life examples like tropical rain and desert dryness help connect concepts to daily life. Designed to support NGSS standard MS-ESS2-4, this resource helps build reading comprehension while reinforcing science content knowledge related to Earth's systems and energy transfer. Great for reading-to-learn lessons and cross-curricular instruction.

CONTENT PREVIEW

The water cycle is the continuous movement of water through Earth’s atmosphere, land, and oceans. This cycle includes key processes like evaporation, condensation, precipitation, and collection. The main factor that controls the water cycle is the Sun. Without the Sun’s energy, the water cycle would not happen. The Sun drives the movement of water by heating up Earth’s surface, especially oceans, lakes, and rivers.

When the Sun warms water, it causes evaporation—the process of liquid water turning into water vapor. This vapor rises into the atmosphere. Plants also release water vapor through a process called transpiration. Together, evaporation and transpiration add moisture to the air. As water vapor rises and cools, it undergoes condensation and forms clouds. When these clouds become heavy with water droplets, precipitation occurs as rain, snow, sleet, or hail.

The Sun not only powers evaporation but also helps shape weather patterns. It affects wind, temperature, and the movement of air masses, all of which influence how and where precipitation falls. For example, in warmer climates, more sunlight leads to higher evaporation rates, which often means more rainfall.

Real-world examples show the Sun’s power in action. In tropical areas, the intense sunlight causes rapid evaporation, leading to frequent rainstorms. In contrast, deserts receive lots of sunlight but little moisture to evaporate, so they remain dry. Even seasonal changes in sunlight affect the water cycle, such as spring snowmelt that leads to increased river flow.

Understanding how the Sun controls the water cycle helps scientists predict weather, manage water resources, and study climate change. The Sun is essential to life on Earth, and its role in the water cycle is one of the most important ways it supports ecosystems around the planet.

Fun Fact: The Sun releases more energy in one second than humans have used in all of history!

What is the main factor that controls the water cycle?

The MoonThe WindThe SunThe Clouds

What process changes liquid water into water vapor?

PrecipitationEvaporationCondensationCollection

What happens when water vapor cools in the atmosphere?

It turns into snowIt disappearsIt forms cloudsIt sinks to the ground

What is the term for plants releasing water vapor?

TranspirationCondensationEvaporationPrecipitation

How does the Sun affect rainfall in tropical areas?

It stops all precipitationIt reduces wind patternsIt increases evaporationIt cools the ocean

Why are deserts dry despite a lot of sunlight?