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Comparison Matrix Chart – Weather Instruments
Weather
Information being
Measured
Instrument(s) Used…(state the
ones listed in italics in the
text)
How it Works
thermoresistor
As temperature changes, a resistor reduces the current (flow of electrons) in the
device. The current change is converted to a number displayed on the screen.
Temperature
Rain guage
Precipitation
Tipping bucket rain guage
Atmospheric
Pressure
Humidity
Aneroid barometer



Hygrometer:
Sling psychrometer
Analog hygrometer
Digital hygometer
A cylinder-shaped “cup” with a wide top to catch rain and “tick marks” on the side
to measure the volume in mm.
Rain enters through the top funnel and into one of two small buckets. When one
bucket fills up, it tips and forces the other bucket to start catching the drips.
They alternate. When each bucket tips, the rain amount is measured electronically.
An aneroid cell holds air and is sealed off from the outside. Outside air pushes on
it (a lot or a little) and changes the volume. Changes in volume cause a needle to
point to a numerical reading.
 Dry-bulb thermometer measures air temp, Wet-bulb thermometer
measures temp. after evaporation occurs. The difference in temperatures
shows relative humidity, looked up in a table
 Uses a hair. The hair absorbs water from air and expands. Hair is attached
to an axle. Getting longer means turning the axle to point a needle to a
number
 Water vapor gets on a silicon plate and causes electricity to flow. More
humid = more electricity. This gets displayed on a digital monitor.
Weather
Information being
Measured
Wind Speed and
Direction
Temperature,
pressure,
humidity, wind
speed, direction
Precipitation
Cloud cover,
pressure systems,
infrared
radiation,
precipitation,
haze & pollution
Instrument(s) Used…(state the
ones listed in italics in the
text)
How it Works
Anemometer (speed)

wind vane (direction)
Beaufort Scale (speed…
qualitative)

Weather Balloons
Weather radar
Weather Satellites

“cups” catch the wind and spin around. The rotation rate is
measured (speed = distance/time)
Arrow with pointed end and a “tail”, finned end. Wind points
the arrow in the direction it is travelling
0-12 scale based on observations (see p.53), translating to a
speed in km/h
A radiosonde has many measuring instruments and is put into the
balloon. It rises and eventually bursts but the data is sent by radio
transmitters to the meteorologists.
Radio waves are sent out and reflect off precipitation. The more precipitation, the
more reflection. These reflected signals are converted to colored images. The time
it takes to get the signal back shows WHERE the precipitation is happening.
Sensors which orbit the earth from high above (800-36000 km above
the surface of earth) either in a spot that stays above the SAME
PLACE on earth or that CRICLES THE WHOLE EARTH. Data is sent
back to meteorologists remotely.