Weather Instruments
Weather Satellite and Satellite Images
Satellite What is it? What kinds of data can it take? Atmospheric temperature Surface temperature Wind speed Water temperature Wave heights What is it? A man-made, electronic satellite which transmits information about current weather patterns to the ground from space.
Compass
Compass To what directions does it point? Cardinal North South East West Intermediate Northeast Southeast Northwest Southwest What is it? A device that is used to find direction by means of a needle that always points north
Wind Vanes
Wind Vane What is it? An object that is usually put on the top of a roof and that has an arrow that turns as the wind blows to show the direction of the wind
Anemometers
Anemometer What is it? An instrument for measuring and indicating the force or speed of wind. How does a Cup Anemometer work? 3 metal cups attached to the ends of horizontal arms mounted on a vertical shaft. Wind catching in the cups causes them to revolve. This action turns the shaft which is connected to a dvide that gives the wind speed in miles per hour.
Rain Gauge
Rain Gauge What is it? An instrument used to measure precipitation. How does it work? A standard rain gauge consists of a funnel leading to a measuring tube. The area of the circular top of the funnel is 10 times that of the tube's cross section, so that one inch of water falling on the funnel will rise to 10 inches in the tube. The tube thus multiplies the height of the fallen water by 10, making it possible to measure small amounts of precipitation.
Sling Psychrometers
Sling Psychrometer What is it? Measures relative humidity, using the cooling effect of evaporation How does it work? 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 theat thermometer to be lower than the other.
Barometer
Barometer What is it? A device for measuring atmospheric pressure (the pressure resulting from the weight of the air above a given point) How is it used? A change in atmospheric pressure is a sign of changing weather. A “falling” barometer, indicating reduced pressure, shows that a low-pressure mass of air is approaching. A “rising” barometer generally means an approaching high- pressure air mass and fairer weather.
Thermometer
Thermometer What is it? An instrument for measuring temperature How does it work? The measurement is always indirect—that is, it is a measurement not of temperature itself but of the effect of temperature on some physical property of a material used in the thermometer. In response to changes in temperature, for example, solids, liquids, and gases expand and contract; the pressure of a gas that is kept at a constant volume changes; and the electrical resistance of a metal or alloy increases and decreases.