Download Weather Instrumentation

Weather Instrumentation
7th Grade Science
Mr. Bombick
Weather Instruments
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Thermometer
Barometer
Hygrometer
Rain Gauge
Anemometer
Doppler Radar
Satellites
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
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
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
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
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 90o angle perpendicular to a
horizontal line)
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
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
The End