Weather Instruments

Unit 2

What is weather?

• Weather is the day-to-day conditions of a particular place.

What is climate?

• The climate is the common, average weather conditions at a particular place over a long period of time (for example, more than 30 years).

Weather Instruments

• Different weather instruments are used daily to measure many aspects of conditions throughout the world.

Thermometer

• A thermometer measures air temperature.
• Most thermometers are closed glass tubes containing a liquid like alcohol or mercury.
• When air outside the thermometer heats the liquid, the liquid expands and moves up the tube.

Barometer

• A barometer measures air pressure.
• It tells you whether the pressure is rising or falling.
• There are two types of barometers, the mercury barometer, and the aneroid barometer.

Mercury Barometer (left)

​

​

​

Aneroid Barometer (right)

Sling Psychrometer

• A sling psychrometer measures relative humidity, with the cooling effect of evaporation.
• Two thermometers are used in a sling psychrometer. Wet the cloth of one of the thermometers and swing the psychrometer around a few times. Water evaporates from the cloth, causing the temperatures on that thermometer to be lower than the other.

Rain Gauge (ombrometer)

• A rain gauge measures the amount of rain that has fallen over a specific time period.

Wind Vane

• A wind vane is an instrument that determines the direction from which the wind is blowing.

Anemometer

• An anemometer measures wind speed. The wind turns the dial attached to the instrument and shows the wind speed.

Weather Map

• Weather maps indicate atmospheric conditions above a large portion of Earth’s surface. Meteorologists use weather maps to forecast the weather.
• Meteorology is the study of weather and atmosphere.

Hygrometer

• A hygrometer measures the water vapor content of air, or humidity. Its function is similar to that of a sling psychrometer.

Weather Balloon

• A weather balloon measures weather conditions higher up in the atmosphere.

​

Compass

• A compass is a navigational instrument that measures direction.

Weather Satellite

• Weather satellites are used to photograph and track large-scale air movements. Then meteorologists compile and analyze the data with the help of computers.

Doppler Radar

• Doppler Radar is a electronic instrument that measures precipitation intensity (we’ll cover this later).

Pyranometer

• A pyranometer measures solar irradiance (solar power, or just sunlight). They are typically found next to solar panels.

Solar Radiation Shield

• A solar radiation shield is used by weather stations to protect their temperature and humidity sensors from solar radiation and other forms of radiated or reflected heat.