The document discusses how the sun provides heat to Earth and the factors that influence temperature variations across our planet's surface. It can be summarized as follows: 1) Insolation from the sun differentially heats Earth's surface depending on latitude, the tilt of Earth's axis, and surface albedo. Darker surfaces absorb more heat while lighter surfaces reflect more. 2) Temperature decreases with increasing altitude and aspect, with south-facing slopes receiving more sunlight in the Northern Hemisphere. 3) Bodies of water heat and cool more gradually than land due to their higher specific heat capacity, moderating surrounding air temperatures.

1. The Sun
Our Heat Source

2. Insolation
 Insolation is incoming solar radiation that heats our
planet.
 Round surface of Earth + 23.5° tilt on axis = differential
heat distribution

3. Insolation and Latitude

5. Absorption vs Reflection
 Albedo: % of solar radiation reflected back into space
 Light surfaces = high  Dark surfaces = high
albedo absorption
 Causes uneven (differential) heating of Earth’s surface

6. Albedo

7. Lapse Rate
 A drop in temperature as altitude (or elevation)
increases
 -1°C for every 150m in elevation
 Air is heated by the Earth’s surface, not by the Sun

8. Lapse Rate and Altitude

9. Temperature and Altitude

10. Aspect
 The compass direction a slope is facing
 In the Northern hemisphere…
 South-facing slopes get more sunlight

11. Aspect

17. Solar Energy Received
• Although the greatest intensity of solar radiation
occurs at the time of the summer solstice, in the
Northern Hemisphere the months of July and August
are generally the warmest of the year.
• Conversely, in the Northern Hemisphere a minimum
of solar energy is received in December at the time of
the winter solstice, but January and February are
usually colder.

18. Varying Temperatures
hot
cold
water solid
Convective heat transfer Conductive heat
allows for deeper mixing transfer is shallow
(more efficient) (less efficient)

19. Specific Heat of Various Substances
4.5
Specific Heat: The amount of heat needed to
4 raise the temperature of a substance 1deg C.
Because the specific heat is much greater for
3.5 water than for land it takes more energy to warm
Hg
water than it does land.
3 Cu
Specific Heat
Fe
2.5
SiO2
2 CaCO3
O2
1.5
Land
1 H2O
0.5
0
Hg Cu Fe SiO2 CaCO3 O2 Land H2O
Substances
Specific heat: the heat (heat energy) need to raise the temperature of one gram of a
substance 1° C. The higher the heat capacity the more energy needed to raise the
temperature of that substance.

20. Varying Temperatures
 Water  Land
 Heat can penetrate  Denser
deeper  Heats quickly, but only
 Water moves = mixing to a shallow depth
and spreading of heat  At night, cools quickly
 At night, retains much  Inland locations
of the heat  Summer = hot
 Coastal locations
 Winter = cold
 Summer = moderate
 Winter = moderate

21. Temperature
• Temperature is one of the most basic elements of weather
and climate.
• The daily mean temperature is determined by averaging the
24 hourly readings or by adding the maximum and minimum
temperatures for a 24-hour period and dividing by two.
• The daily temperature range is computed by finding the
difference between the maximum and minimum
temperatures.
• Other temperature data:
• monthly mean temperature
• annual mean temperature
• annual temperature range

22. Temperature Scales
• The three common temperature scales used to measure
temperature are:
• (1) the Fahrenheit scale, which is defined by using the
ice point (32°) and steam point (212°),
• (2) the Celsius scale, a decimal scale on which the
melting point of ice is set at 0 and the boiling point of
water at 100°, and
• (3) the Kelvin or absolute scale, where the zero point
represents the temperature at which all molecular
motion is presumed to cease (called absolute zero), the
ice point is set at 273, and the steam point at 373.

23. Human Perception of
Temperature
• The heat stress index (or heat index), a commonly
used expression of summertime discomfort, links
humidity and temperature to determine the
thermal comfort of the human body.
• Wind chill, a typical wintertime index, uses both
wind and air temperature to calculate the human
sensation of temperature.

25. Warm Ocean Currents

26. Earth’s Energy Budget
 Balance between incoming solar radiation and
outgoing infrared radiation
 Solar Radiation  Infrared Radiation
 Incoming  Outgoing
 Shortwave  Longwave
 Heats our planet  Lost to outer space

27. Energy Budget

28. Distribution of Heat
 Warm land or water bodies heats air above
 Warm air rises (Convection) = low air pressure
 Cold air sinks = high air pressure
 Wind = air pushing from high to low pressure areas
 Water moves heat in the same manner

29. WIND

30. Urban Heat Island

32. Urban Heat Island
Atlanta, Georgia