Weather Instruments

Weather Satellite

and Satellite Images

Satellite

What is it?A man-made,

electronic satellite which transmits information about current weather patterns to the ground from space.

What kinds of data can it take? Atmospheric

temperature

Surface temperature

Wind speed

Water temperature

Wave heights

Compass

Compass

What is it?A device that is

used to find direction by means of a needle that always points north

To what directions does it point?

Cardinal

North

South

East

West

Intermediate

Northeast

Southeast

Northwest

Southwest

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

ThermometerWhat 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.