12.3 Gathering Weather Data
1. Meteorologists use many
different instruments to make
measurements to determine the
weather.
2. A ________________
thermometer
is a device used to
measure temperature.
3. A _________________
barometer
is a device used
to measure air pressure.
anemometer
4. An ________________
is used to measure
wind speed.
hygrometer
5. A _______________
measures relative
humidity.
6. A rain gauge measures rain fall.
7. A ceilometer measures the height of
cloud layers and estimates the amount of
sky covered by clouds.
8. Radar helps meteorologists by
being able to more accurately
know where rain is falling.
Dec. 2
It works by sending out electromagnetic waves and those
waves bounce off of large rain drops. The scattering of
the waves is then detected by antennae and sends the
information back to a computer which processes it and
puts it into a map.
9. The Doppler Effect is a phenomena
that explains the changing frequency of
waves when they are coming towards a
point versus when the wave is traveling
away.
Example: the change in pitch of a
train whistle as it comes towards you
versus when it has passed. It has a higher
frequency when coming because the
waves are compressed and a lower
frequency when it has passed as the wave
expands out behind. See p. 315.
The Doppler Effect
Doppler Effect Video
10. Using this type of radar allows
meteorologists to “see” where rain is
moving towards and away from the radar
station. It also informs them on wind
speeds which allows them to note where
a tornado may be forming.
11. Weather satellites are also useful in
determining the weather. Cameras mounted
on satellites take pictures at regular intervals
and sends them back to earth. Satellites can
only detect where the clouds are, so that is
not necessarily precipitation.
Hurricane Katrina
12. Infrared imagery allows cameras to
take pictures in the dark. It detects
differences in thermal energy and projects
them in different colors.
Hurricane Katrina
13. A station model is a record of
weather data for a particular site at a
particular time.
-Different symbols represent different
conditions.
14. An isoline is a line that connects
points of equal or constant value.
15. An isobar connects points with equal
pressures.
Close
isobars
indicate dramatic
pressure
differences and
strong winds.
16. An isotherm connects points with
equal temperatures.
Weather Data
•
•
•
•
•
•
•
Surface Data:
Thermometer: Measures temperature
Barometer: Measures Air Pressure
Anemometer: Measures wind speed
Hygrometer: Measures relative humidity
Rain Gauge: Measures rain fall
Ceilometer: Measures Cloud Height & Estimates
% of sky covered
Radar
• Radar helps locate rain. Waves are emitted and when
they come into contact with large enough water
droplets they scatter. These scattered waves are
picked up by another antenna.
• Doppler Radar: As train passes you the sound
changes. This change in waves can be used to gauge
where rain is.
Satellites
• Orbiting Satellites use visible and infrared
imagery to observe the atmosphere.
– Allows more accurate forecasting
Analyzing Data
• Meteorologist use station model to record
and plot data.
• Forecasting accuracy decreases with time.
Isopleth
• Isobars are used to tell us the common pressure
areas. Isobars= common temperature
• Close isobars indicate dramatic pressure
differences and strong winds.