Thermometers are kept in a shelter that has plenty of ventilation to get a true reading of air temperature. Direct sunlight hitting the thermometer would make it read unrealistically high. Thermometers are usually 5 to 6 ft above the ground.

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Thermometers are kept in a shelter that has
plenty of ventilation to get a true reading of
air temperature. Direct sunlight hitting the
thermometer would make it read unrealistically
high. Thermometers are usually 5 to 6 ft above
the ground.
2
On a calm afternoon the ground and air near the
ground may have temperatures much higher than
recorded by the thermometer.
3
When the wind picks up the air mixes and so the
difference in temperature between the near
surface air and air higher up is reduced.
4
The maximum temperature is reached during the
time of day when the incoming solar energy
matches the outgoing longwave (terrestrial)
energy. In the diagram this occurs at 4 PM. So
the maximum temperature does not occur at the
same time as the maximum sunlight.
5
On a calm evening the ground and air near the
ground may have temperatures much colder than
recorded by the thermometer. The ground radiates
away energy much better than does the air.
6
When the wind picks up the air mixes and so the
difference in temperature between the near
surface air and air higher up is reduced.
7
Orchard heaters help prevent frost damage to
trees.
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Mixing the air with large fans helps prevent
frost damage to trees.
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Sprinkler systems can help prevent frost damage
to trees through the release of latent heat
energy as the water freezes to ice.
Fig. 3-19, p. 70
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Controls of Temperature
Before looking at the next slide, try to list as
many physical features that might influence the
temperature and precipitation of a region like
western WA.
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Controls of Temperature
Latitude Time of year Altitude Cloud cover Land
Water proximity Ocean currents Mean air
flow Mean Wind speed and direction Mountains Othe
rs??
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In winter the Pacific ocean is warmer at most
latitudes than the land areas in United States
Fig. 3-20, p. 72
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In summer the Pacific ocean is cooler at most
latitudes than the land areas in United States.
Also comparing this slide with the previous, the
difference (or range) in temperature between
summer and winter is larger for land areas than
for oceans
Fig. 3-21, p. 72
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The daily range in temperature (daytime high
night time low) is smaller as you travel up a
very high building.
Fig. 3-22, p. 73
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Fig. 3-23, p. 74
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Fig. 3-24, p. 74
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On a local level for a given day, temperatures
fluctuate drastically from year to year.
Fig. 4, p. 75
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Extra credit idea. Summarize how heating degree
days and cooling degree days are defined and
parcticaly used.
Fig. 3-25, p. 76
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Fig. 3-26, p. 76
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1st Thermometer. Galileo invented a rudimentary
water thermometer in 1593 which, for the first
time, allowed temperature variations to be
measured.
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Maximum thermometer for reading the maximum
temperature during a 24 hr period.
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Minimum thermometer for reading the minimum
temperature during a 24 hr period.
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A thermograph. These are becoming obsolete
through the deployment of computer data loggers
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Between roughly 35 N and 35 S Earth receives more
sunlight than it radiates back to space via
longwave radiation. Poleward of these latitudes
Earth receives less sunlight than it radiates
back to space via longwave radiation. The
surplus and deficit are balanced by energy
transport in the atmosphere and oceans.
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The angular position of direct sunlight changes
throughout the year. In the above diagram the
direction of the solar collector is adjusted to
an average position.
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