1. Weather Instrumentation 7 th Grade Science Mr. Bombick

2. Weather Instruments Thermometer Barometer Hygrometer Rain Gauge Anemometer Doppler Radar Satellites

3. Thermometer Relies on the measurement of temperature by the property of matter to expand with thermal energy or emit thermal radiation Common thermometers using mercury or alcohol measure increasing temperature by expansion of liquid by thermal energy Thermistor is an electronic component that changes its resistance with changing thermal energy Thermocouple is a metal component that expands and contracts with changing thermal energy (the movement of the metal component is measured to give the temperature) Infrared thermometer examines the amount of infrared energy being emitted from the object Galileo thermometer uses enclosed balls with solutions of different densities that float at different temperatures

4. Barometer Barometers measure the atmospheric pressure Barometers come in two major types-mercury and aneroid Mercury barometers examine the rise of mercury in a tube of an open system with the air Aneroid barometers measure the expansion of a metal spring in an enclosed container that expands or contracts because of changes in air pressure

5. Hygrometer A hygrometer measures the relative humidity of the air Types of hygrometers include metal/pulp coil, hair tension, resistive electronic, capacitive electronic, thermal conductivity, and chilled mirror dew point electronic hygrometers Metal/pulp coil hygrometers are common and rely on the changes of a salt-impregnated paper strip to move a metal coil with changing water levels in the air (these are also inaccurate and hard to keep calibrated) Hair tension hygrometers rely on the changes in the length of hair with changing relative humidity The electronic hygrometers are usually more accurate (the chilled mirror dew point hygrometer is the most accurate) and stay calibrated for longer periods of time

6. Rain Gauge Measures the amount of precipitation over a period of time Standard rain gauge relies on collection of precipitation over time using a standard size graduated cylinder (0.2 mm increments) Gravimetric rain gauges measure the weight of precipitation and calculate the volume based on weight (the advantage of this rain gauge is that it is precipitation type independent) Tipping bucket rain gauge is an instrument that contains a bucket that is tipped after a a known quantity of precipitation fills the bucket (the amount of “tips” is recorded and total precipitation is calculated) Optical rain gauge uses a laser diode and photo transistor detector that can count drops of waters and calculate total amount of precipitation

7. Anemometer An anemometer measure the wind speed and is often coupled with a device to determine wind direction Types of anemometers include cup, windmill, hot-wire, laser Doppler, and ping pong ball Cup anemometers use cups that catch the wind and rotate around a pole Wind mill anemometers look like an airplane’s propeller that moves with the wind Hot-wire anemometers measure the wind’s cooling effect on a wire that has been heated to a precise temperature Laser Doppler anemometers use the Doppler effect to measure wind speed Ping Pong ball anemometer uses a ping pong ball attached to a string that will move with the wind (the wind speed is calculated from the angle the string moves away from a 90 o angle perpendicular to a horizontal line)

8. Doppler Radar A type of radar that uses microwaves to reflect off atmospheric objects (clouds, dust, and precipitation) The Doppler effect examines the change in wavelength as an object moves toward or away from an object Using the Doppler effect the speed of atmospheric objects can be calculated Doppler radar is very important in determining the nature of storm fronts and predictions of possible tornadic activity

9. Weather Satellites Weather satellites are instrumental in measuring weather phenomena Weather satellites can record visual information such as clouds, particulate concentrations, hurricanes, and typhoons Weather satellites can also measure temperatures using infrared technology

10. The End