Download CH 3 - Building The Pride

Survey
yes no Was this document useful for you?
   Thank you for your participation!

* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project

Document related concepts
no text concepts found
Transcript
Seasonal & Daily Temperatures
This chapter discusses:
1. The role of Earth's tilt, revolution, & rotatation
in causing locational, seasonal, & daily
temperature variations
2. Methods & tools for measuring temperature
Seasons & Sun's Distance
Figure 3.1
Earth's surface is 5 million kilometers further from the sun in
summer than in winter, indicating that seasonal warmth is
controlled by more than solar proximity.
Seasons & Solar Intensity
Figure 3.2
Solar intensity, defined as the energy per area, governs earth's
seasonal changes.
A sunlight beam that strikes at an angle is spread across a greater
surface area, and is a less intense heat source than a beam
impinging directly.
Solstice & Equinox
Figure 3.3
Earth's tilt of 23.5° and revolution around the sun creates seasonal
solar exposure and heating patterns.
A solstice tilt keeps a polar region with either 24 hours of light or
darkness.
A equinox tilt perfectly provides 12 hours of night and 12 hours of
day for all non-polar regions.
24 Hours of Daylight
Figure 3.4
Summer north of the artic circle will reveal a period of 24 hour
sunlight, where the earth's surface does not rotate out of solar
exposure, but instead experiences a midnight sun.
Earth's Tilt & Atmosphere
Figure 3.5
Figure 3.6
Earth's atmosphere reduces the amount of insolation
striking earth's surface.
Earth's atmosphere and tilt combine to explain variation in
received solar radiation.
Earth's Unequal Heating
Figure 3.7
Incoming solar radiation is not evenly distributed across all lines of
latitude, creating a heating imbalance.
Earth's Energy Balance
Earth's annual
energy balance
between solar
insolation and
terrestrial infrared
radiation is
achieved locally at
only two lines of
latitude.
A global balance is
maintained by
excess heat from
the equatorial
region transferring
toward the poles.
Figure 3.8
Longer Northern Spring & Summer
Figure 3.9
Earth reaches its greatest distance from the sun during a northern
summer, and this slows its speed of revolution.
The outcome is a spring and summer season 7 days longer than that
experienced by the southern hemisphere.
Local Solar Changes
Northern
hemisphere
sunrises are in
the southeast
during winter,
but in the
northeast in
summer.
Figure 3.10
Summer noon
time sun is
also higher
above the
horizon than
the winter
sun.
Landscape Solar Response
Figure 3.11
South facing slopes receive greater insolation, providing energy to
melt snow sooner and evaporate more soil moisture.
North and south slope terrain exposure often trigger differences in
plant types and abundance.
Daytime Warming
Solar radiation heats the
atmosphere from below by soil
conduction and gas convection.
Figure 3.12
Winds create a forced convection
of vertical mixing that diminishes
steep temperature gradients.
Figure 3.13
Temperature Lags
Earth's surface
temperature is a
balance between
incoming solar
radiation and outgoing
terrestrial radiation.
Peak temperature lags
after peak insolation
because earth
continues to warm
until infrared radiation
exceeds insolation.
Figure 3.14
Nighttime Cooling
Figure 3.15
Figure 3.16
Earth's surface has efficient radiational cooling, which creates a
temperature inversion that may be diminished by winds.
Evening length, water vapor, clouds, and vegetation affect earth's
nighttime cooling.
Cold Dense Air
Figure 3.17
Nighttime radiational cooling increases air density.
On hill slopes, denser air settles to the valley bottom, creating a
thermal belt of warmer air between lower and upper cooler air.
Protecting Crops from Below
Figure 3.18
Figure 3.19
Impacts of radiational cooling can be diminished by orchard
heaters creating convection currents to warm from below and by
wind machines mixing warmer air from above.
Protecting Crops from Above
Crops subjected
to below freezing
air are not helped
by convection or
mixing, but by
spraying water.
The cold air uses
much of its
energy to freeze
the water, leaving
less to take
temperatures
below 0° C that
damage the crop.
Figure 3.20
Controls of Temperature
Earth's air temperature is governed by length of day
and intensity of insolation, which are a function of:
1) latitude
Additional controls are:
2) land and water
3) ocean currents
4) elevation
January Isotherms
Latitude
determines that
earth's air
temperatures are
warmer at the
equator than at
the poles, but
land and water,
ocean currents,
and elevation
create additional
variations.
Figure 3.21
July Global Isotherms
The southern
hemisphere
has fewer land
masses and
ocean currents
that encircle
the globe,
creating
isotherms that
are more
regular than
those in the
northern
hemisphere.
Figure 3.22
Daily Temperature Range
Earth's surface
efficiently
absorbs solar
energy and
efficiently
radiates infrared
energy, creating a
large diurnal
temperature
range (max min) in the lower
atmosphere.
Figure 3.23
Regional Temperatures
Regional differences in
temperature, from annual or
daily, are influenced by
geography, such as latitude,
altitude, and nearby water or
ocean currents, as well as heat
generated in the urban area.
Figure 3.24
Heating Degree Day
Figure 3.25
Temperature data are analyzed to determine when living space will
likely be heated (e.g. when below 65° F) and how much fuel is
required for that region.
Cooling & Growing Degree Days
Figure 3.26
Daily temperature data are also used to determine cooling loads for
living space above 65° F, as well as growing hours for specific crops
above a base temperature.
Recording Thermometer
Figure 3.27
Figure 3.28
Non-digital thermometers recorded maximum and minimum
temperature using simple designs to temporarily trap the
mercury or a marker along the thermometer scale.
Technological Upgrades
Pen and lever recording drums
required regular calibration for
accurate data.
Figure 3.29
Modern weather stations
predominantly use digital data
recording techniques that are
less likely to introduce data error
and generate data more readily
analyzed by computers.
Figure 3.30