Thermometers

• Perhaps the most well-known weather measuring tool, thermometers indicate the temperature. These instruments contain a tube filled with a liquid. When liquids get warmer, they expand and rise in the tube. Conversely, cooler liquids contract, causing the level to fall in the thermometer.
  
  

Barometers

• Meteorologists have used barometers to measure air pressure, or the weight of the air, since 1643. The standard barometer consists of a tube of mercury placed upside down in a bowl that is also filled with mercury. An increase in atmospheric pressure presses down on the mercury in the bowl which in turn causes the level of the mercury in the tube to rise. Increases of air pressure indicate that a cold front has passed over your location. When the air pressure drops, a storm is likely approaching.
  
  

Precipitation Gauges

• Precipitation gauges measure how much rain, snow and ice has fallen in a location. Meteorologists have used this tool for over a century. Basic versions of precipitation gauges consists of a clear plastic container with a ruler. When precipitation falls, it collects in the container. The ruler measures the number of inches of precipitation.
  
  

Anemometers

• Anemometers measure wind speed and direction. These tools consist of two distinct parts. The first is a metal pole with cups attached around the center. When the wind blows, the cups rotate. The speed at which the cups spin depends on the wind speed. The second part of an anemometer is the wind vane, or weather vane. Weather vanes have one end that catch the breeze. The other end points to the direction that the wind is coming from.