Weather Instruments

Weather scientists, called meteorologists, use many tools to measure the weather. Thermometers measure temperature. Barometers measure air pressure. Rain gauges measure how much rain has fallen. These tools help us understand and predict the weather.

Measuring Temperature and Rain

A thermometer measures how hot or cold the air is. Most thermometers use a liquid that expands when heated. A rain gauge is a simple tube that collects rain. By measuring the water in the tube, scientists know how much rain fell. A hygrometer measures humidity, or how much moisture is in the air.

Measuring Wind and Pressure

An anemometer measures wind speed. It has cups that spin faster when the wind blows harder. A wind vane shows which direction the wind is blowing from. A barometer measures air pressure. Falling air pressure often means a storm is coming. Rising pressure usually means clear weather ahead.

Fun Facts

• The thermometer was invented in the early 1600s.
• Weather balloons carry instruments up to 100,000 feet to measure conditions high in the atmosphere.
• Doppler radar can detect rain, snow, and even tornadoes from hundreds of miles away.

Did You Know?

The first barometer was invented in 1643 by an Italian scientist named Evangelista Torricelli. He used a tube filled with mercury to measure air pressure!