Anemometer: An instrument used for measuring the speed of wind.
How does it work:
· It consists of 4 metal cups attached to the ends of horizontal arms mounted on a vertical rod.
· Wind catching in the cups causes them to revolve.
· This action turns the rod, which is connected to a device that gives the wind speed in miles per hour, km per hour, or knots.
Barometer:
· An instrument used to measure atmospheric pressure (the pressure resulting from the weight of the air above a given point).
· Used to determine altitude
· Used to determine weather changes
· Written in millibars
How does it work:
· A falling barometer, indicating reduced pressure, shows that a low-pressure mass of air is approaching. Such low-pressure systems bring storms.
· A rising barometer generally means an approaching high-pressure air mass and fairer weather.
Hygrometer: Used to measure the humidity in the air
How does it work?
· It uses a paper strip that is saturated with salt to absorb humidity.
· The paper is connected to a metal coil, and the addition of moisture changes the shape of the coil.
· A dial notes the changes in the coil.
Psychrometer: A type of hygrometer that has a wet-bulb and a dry-bulb thermometer to determine relative humidity.
How does it work?
When a reading is to be taken, the wick is first dipped in water and then the instrument is whirled around.
· During the whirling, the water evaporates from the wick, cooling the wet-bulb thermometer. Then the temperatures of both thermometers are read.
· If the surrounding air is dry, more moisture evaporates from the wick, cooling the wet-bulb thermometer more so there is a greater difference between the temperatures of the two thermometers.
· If the surrounding air is holding as much moisture as possible - if the relative humidity is 100% - there is no difference between the two temperatures.
Rain Gauge: An instrument used to measure precipitation and the amount of rainfall.
· How does it work: A rain gauge works by collecting rain in a measurement tube.
· Typically, this tube is a clear plastic or glass vial with graduated markings to show water accumulation.
Thermometer: Measures temperature in Celsius or Fahrenheit.
Conversions:
· For Celsius to Fahrenheit use this formula:C = 5/9 (F-32)
· For Fahrenheit to Celsius us this formula: F = 9/5 (C+32)
How does it work? A common thermometer uses mercury in a glass tube. An increase in temperature makes the mercury expand and rise in the glass tube.
Wind Vane: An instrument used to show the direction of wind; also called a weather vane
How does it work?
· wind vane works by wind blowing against a large surface to measure the wind direction. A wind vane has a front end and a tail end. The tail end is the larger of the two areas and causes the front end to point in the direction that the wind is blowing.
· A wind vane is typically mounted on top of a post or a roof.
· The device rotates freely and points to the direction the wind is blowing from.