Weather Characteristics and Tools

1. Weather Characteristics and Tools http://www.katrina.noaa.gov/images/katrina-08-28-2005.jpg

2. Weather: Characteristics and Tools Characteristic Tool Description Thermometer Temperature Precipitation (Rain) Rain Gauge Psychrometer Humidity Barometer Pressure Anemometer Wind (speed/direction)

3. Weather: Characteristics and Tools Thermometer A thermometer measures heat energy. Temperature is measured in units called degrees. There are three different scales in use today. Fahrenheit is most commonly used in the united states. Celsius is the standard scientific unit all over the world. Kelvin is like Celsius, except zero is set at "absolute zero", where molecules are no longer moving. Molecules of the liquid (mercury or alcohol) are sealed in a glass tube. The molecules of the liquid will move faster and spread out when they come into contact with something warm (transfer of energy through conduction). When the molecules spread out the liquid expands and moves up the tube.

4. Weather: Characteristics and Tools Rain Gauge A device that collects precipitation and allows us to measure the height of the water in the container.

5. Weather: Characteristics and Tools Characterisitic: Humidity

6. Weather: Characteristics and Tools Psychrometer The psychrometer, sometimes called the wet-and-dry bulb hygrometer, has two thermometers mounted side by side. The dry-bulb thermometer—measures the temperature of the air. The bulb of the other thermometer is covered with a cloth that is wetted and the water is then evaporate by whirling the psychrometer in the air. As the water evaporates, the bulb is cooled. In general, the drier the air, the greater is the drop in temperature. The relative humidity is determined by comparing the readings of the two thermometers with published psychrometric tables or charts. There are several types of hygrometers. One common type contains animal fibers, usually human hair, that stretch when the relative humidity increases and contract when it decreases. The fibers are usually attached to levers that turn the pointer on a dial.

7. Weather: Characteristics and Tools Psychrometer

8. Weather: Characteristics and Tools Barometer Barometer, a device for measuring atmospheric pressure (the pressure resulting from the weight of the air above a given point). Because a change in atmospheric pressure is a sign of changing weather, this instrument is one of the chief tools of the weather forecaster. A falling" barometer, shows that a low-pressure mass of air is approaching usually bring storms. A rising" barometer generally means an approaching high-pressure air mass and fairer weather.

9. Weather: Characteristics and Tools Weather Balloon

10. Weather: Characteristics and Tools Weather Satellites

11. Weather: Characteristics and Tools Doppler Radar