What Is Weather — Reading Comprehension Lesson

Reading Passage

What Is Weather

Weather is the condition of the atmosphere at a specific place and time. It includes temperature, precipitation, humidity, wind, cloudiness, and atmospheric pressure. Weather is different from climate: weather describes what is happening outside right now or over the next few days, while climate describes the average weather conditions for a region over many decades. The same place can have very different weather on different days — a thunderstorm on Monday, sunshine on Tuesday, and snow on Wednesday — but its climate remains relatively stable over years.

Temperature is the measure of how warm or cold the air is, caused by the amount of heat energy in the atmosphere. The sun is the ultimate source of almost all weather energy: it heats Earth’s surface unevenly because different surfaces (land, water, pavement, forests) absorb and release heat at different rates, and because the sun’s rays strike at different angles depending on latitude and season. These temperature differences drive the movement of air masses, create pressure differences, and set the atmosphere in motion. The atmosphere is constantly trying to equalize temperature differences, and this process drives most weather.

Humidity is the amount of water vapor in the air. Warm air can hold more water vapor than cold air — when air cools, it can no longer hold as much water vapor, and the excess condenses into tiny water droplets that form clouds or fog. The temperature at which air becomes saturated and condensation begins is called the dew point. When water droplets in clouds combine and grow heavy enough, they fall as precipitation: rain, snow, sleet, or hail, depending on temperature conditions. Precipitation returns water to Earth’s surface, completing the water cycle.

Wind is the horizontal movement of air from areas of high pressure to areas of low pressure. Atmospheric pressure is the weight of the air above a given point. Areas of rising warm air create low pressure at the surface; areas of sinking cool air create high pressure. Air always flows from high to low pressure, creating wind. The greater the pressure difference, the stronger the wind. Earth’s rotation deflects wind to the right in the Northern Hemisphere and to the left in the Southern Hemisphere — a phenomenon called the Coriolis effect — creating the large-scale global wind patterns that influence weather around the world.

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