Scientists use special tools to measure weather. A thermometer measures temperature (how hot or cold the air is). A rain gauge measures how much rain has fallen. A wind vane shows which direction the wind is blowing, and an anemometer measures how fast the wind is moving. Measuring weather with tools gives us exact numbers instead of just guesses, which helps us compare weather from day to day and place to place.
Set up a simple classroom weather station with a thermometer, rain gauge, and wind vane. Have students take readings at the same time each day and record them in a table or chart. Compare readings across days and weeks to discover patterns. Making and reading a rain gauge from a plastic bottle is a powerful hands-on activity.
You already know how to describe weather by looking outside and feeling the air. But weather scientists need more than descriptions -- they need exact measurements. Saying "it is warm today" does not mean much because warm feels different to different people. Saying "it is 28 degrees Celsius today" gives a precise number that everyone understands the same way. That is why we use weather tools.
The most familiar weather tool is the thermometer. A thermometer measures the temperature of the air -- how hot or cold it is. Most thermometers use a liquid (like alcohol colored red) inside a glass tube. When the air gets warmer, the liquid expands and rises up the tube. When the air gets cooler, the liquid contracts and drops down. By reading the number next to the liquid level, you get the exact temperature. Weather thermometers are placed outside, in the shade, so they measure the air temperature and not the sun heating the thermometer itself.
A rain gauge is a container that collects rainwater. It has markings on the side measured in millimeters or centimeters. After a rainstorm, you read the markings to find out how much rain fell. You can make a simple one from a clear plastic bottle and a ruler. A wind vane (sometimes called a weather vane) is an arrow mounted on a pole that spins to point in the direction the wind is blowing from. An anemometer has cups that spin in the wind -- the faster they spin, the faster the wind is blowing.
Using these tools every day and writing down the measurements is how weather scientists build a record of weather over time. When you record the temperature, rainfall, and wind for weeks and months, you start to see patterns -- like temperatures rising in spring or more rain falling in certain months. Those patterns are the beginning of understanding weather forecasting.