Weather Instruments
Unit 11 - Day 1
Notes
Have a red book
open to page 60.
Thermometer
Thermometers
measure air
temperatures.
Thermometers
work because
matter expands
when heated. Most
thermometers are
closed glass tubes
containing liquids
such as alcohol.
Barometer
A barometer
measures air
pressure.
 There are two
types of
Barometers:
Mercury
Barometer and
Aneroid
Barometer.

A Mercury
Barometer consists
of a glass tube
inserted into a dish
of mercury or
colored denatured
alcohol.
 *(If you build your
own, don’t use
mercury)


The surrounding air
presses down on the
mercury in the dish
and forces some of
the mercury up into
the tube. The
height to which the
mercury rises in the
tube is directly
proportional to the
atmospheric
pressure.
Psychrometer

A psychrometer
measures the
humidity of the
air. One of the
two
thermometers
has a wick (cloth
cover) which is
dipped in
distilled water.


Evaporation of water
from the wick on the
wet bulb
thermometer leads
to cooling.
Using a Relative
Humidity Table, the
temperature
difference between
the two
thermometers gives
the relative humidity
of the air (in
percent).

This is an
example
of the
type of
table you
would
use. Your
book
might
also have
an
example.
One such
psychrometer is
a Sling
Psychrometer.
 Measurements
are taken by
whirling the
psychrometer
with the handle.

Anemometer
An Anemometer
measures the
wind speed. The
cups catch the
winds, turning a
dial attached to
the instrument.
 Think you could
build one of
these?

Time for a little
review!
1.
If I wanted to
find out if the
pressure was
rising, I’d use
which of the
following?
A)
B)
C)
D)
E)
F)
Thermometer
Barometer
Psychrometer
Wind Vane
Rain Gauge
Anemometer
2.This is used
to determine
the relative
humidity.
A)
B)
C)
D)
E)
F)
Thermometer
Barometer
Psychrometer
Wind Vane
Rain Gauge
Anemometer
3. Can help you find
out the wind
speed.
A)
B)
C)
D)
E)
F)
Thermometer
Barometer
Psychrometer
Wind Vane
Rain Gauge
Anemometer
4. If I wanted to
know the
difference
between the
temperature
inside and outside
of the classroom.
A)
B)
C)
D)
E)
F)
Thermometer
Barometer
Psychrometer
Wind Vane
Rain Gauge
Anemometer
How did you do? Here
are the correct answers
1. B. Barometer
2. C. Psychrometer
3. F. Anemometer
4. A. Thermometer