Chapter 4: Insolation and
Temperature
The Impact of Temperature
on the Landscape
• All living things influenced
by temperature
• Adaptation to temperature
extremes
• Temperature affects humanbuilt landscape
• Temperature affects inorganic
landscape components
– Soil and bedrock exposure
Figure 4-1a & 4-1b
Energy, Heat, and
Temperature
• Energy: ability to do work
• Forms of energy
– Kinetic – energy of movement
– Chemical, Potential, Nuclear, etc.
• Temperature
– Heat
• Movement of atoms
– Temperature:
• Measurement of heat
• Temperature scales
– Celsius
– Fahrenheit
– Kelvin
Figure 4-2
Energy, Heat, and Temperature
• The Sun
– Primary source of energy for Earth’s atmosphere
• Properties of Sun
– Average size
star
– Nuclear fusion
– Magnitude of
Sun’s energy
• Energy spreads
as it leaves the
Sun
– Travels through voids in space without loss of energy
Figure 4-3
Energy, Heat, and Temperature
Figure 4-4
• Electromagnetic (EM) energy
– EM spectrum
• Wavelength
– Distance between two wave
crests
• 3 important areas of EM
spectrum
– Visible radiation
– Ultraviolet radiation
• Too short to be seen by the
human eye
– Infrared radiation
• Too short to be seen by the
human eye
Figure 4-5
Energy, Heat, and Temperature
• Insolation
– Incoming solar radiation
– Shortwave energy
• Terrestrial
Energy
– Longwave
energy
– “Earth’s”
energy
Figure 4-16
Basic Heating and Cooling
Processes in the Atmosphere
• Radiation
– When objects emit EM energy
• AKA Heat energy emitted from a body
– Warmer objects radiate more effectively
– Warmer objects emit at shorter wavelengths
Figure 4-6
Basic Heating and Cooling
Processes in the Atmosphere
• Absorption
– Body absorbs radiation
– Good radiator,
good absorber
• Reflection
– Objects repel
electromagnetic
waves
– Opposite of
absorption
Figure 4-7
Basic Heating and Cooling
Processes in the Atmosphere
• Scattering
– Deflection of light waves by molecules and particles
• Transmission
– Electromagnetic
waves pass
completely
through a
medium
– Sunsets
Figure 4-9
Basic Heating and Cooling
Processes in the Atmosphere
• Greenhouse effect
– Some atmospheric gases transmit shortwave radiation, but
not Earth’s longwave radiation
Figures 4-11 & 4-12
– Earth radiation held
in by atmosphere
– Atmospheric blanket
Basic Heating and Cooling
Processes in the Atmosphere
• Conduction
– Transfer of heat energy
across a medium
– Energy moves from
molecule to another
one without changing
molecular positions
• AKA direct heat transfer
by contact
– Molecules become
agitated, then vibrate &
collide with cooler
molecules, transferring
heat energy
Figure 4-13
Basic Heating and Cooling
Processes in the Atmosphere
• Convection
– Heat transfer by vertical
circulation in a moving
substance
– Vertical convection cell
• Warm air gains heat,
expands & rises
• Cool air loses heat,
contracts & sinks
• Advection
– Horizontal transfer of
heat in a moving fluid
– AKA wind
Figure 4-14
Radiation, Conduction & Convection
Operating Simultaneously
13
Basic Heating and Cooling
Processes in the Atmosphere
• Adiabatic Cooling and
Warming
– Change in pressure & thus
temperature of rising or
descending air
• Adiabatic cooling
– Air rises and expands,
molecular collisions
decrease, so temperature
decreases
• Adiabatic warming
– Air sinks and compresses,
collisions increase so
temperatures increase
Figure 4-15
Basic Heating and Cooling
Processes in the Atmosphere
• Latent heat
– Heat released or absorbed during a phase change
– AKA “hidden heat” since latent heat is not felt
– Evaporation: liquid
water is converted
to water vapor
• Cooling process
– Condensation:
water vapor is
converted to liquid
water
• Warming process
The Heating of the Atmosphere
• Balance between shortwave incoming solar radiation &
outgoing longwave solar
radiation
• Albedo
– The higher the albedo, the more
radiation the object reflects
Figure 4-16
The Heating of the Atmosphere:
Global Energy Budget
• Energy in = Energy out
Figure 4-17
The Heating of the Atmosphere:
Global Energy Budget
• Earth does not distribute heat evenly through
space & time
– Cause of weather and climate
18
Variations in Heating by Latitude
and Season
• Angle of incidence
– Angle the Sun’s rays strike Earth’s surface
– The higher the angle, the more intense the radiation
Figure 4-18
Variations in Heating by Latitude
and Season
• Atmospheric obstructions
– Clouds, haze, particulates, etc. decrease insolation
Figure 3-4
Figure 4-20
Variations in Heating by Latitude
and Season
• Day length
– The longer the day, the more
insolation is received
Figure 4-19
Variations in Heating by Latitude
and Season
• Latitudinal
radiation balance
and the world
distribution of
insolation
– Belt of max solar
energy that moves
through the tropics
following the Sun’s
direct rays
Figure 4-21
Land and Water Contrasts
• Land heats and cools more rapidly than water due to:
–
–
–
–
Specific heat
Transmission
Mobility
Evaporative
cooling
Figure 4-23
Land and
Water
Contrast
Implications
• Oceans = more moderate
climates
• Hottest & coldest places
on Earth are interiors of
continents
• N. (land) vs. S. (water)
Hemisphere
Figure 4-24
Mechanisms of Heat Transfer
• Need heat transfer
to prevent constant
warming at tropics
& cooling at poles
• Circulation patterns
in atmosphere and
oceans transfer
heat
Mechanisms of Heat Transfer
• 2 mechanisms move heat poleward in both hemispheres,
driven by latitudinal imbalance of heat
– Atmospheric circulation (Ch 5)
– Oceanic circulation
– Direct relationship between atmospheric and oceanic
circulation
• Air blowing over the ocean
creates major surface ocean
currents
• Heat energy stored by oceans
affects atmospheric circulation
Mechanisms of Heat Transfer
• Northern and southern variations
– Near N. Hemisphere pole, landmasses lie so close that
little flow can enter the Arctic Ocean
– In S. Hemisphere, little
land mass allows for constant
westward belt of ocean
circulation called West Wind
Drift
• Southern Ocean
– (AKA the 5th Ocean)
Mechanisms of Heat Transfer
• Temperature patterns
– Poleward currents transfer warm water poleward
– Equatorial currents transfer cool water equatorward
Figure 4-25
Mechanisms of Heat Transfer
Figure 4-26
• Rounding out the pattern
– NW portions of N.
Hemisphere receive cool
water from Arctic Ocean
– Water pulled away from
western coasts of
continents = upwelling
– Deep ocean circulation
• Global conveyor belt
• Tied to short-term climate
change
Vertical Temperature Patterns
• Environmental lapse rate
– Normal vertical temperature gradient
• Average lapse rate
– 6.5°C/km or 6.5°C/1000m)
• Temperature
inversions
– Surface
inversions
– Upper air
inversions
Figures 4-27 & 4-28
Global
Temperature
Patterns
• Global temperature
maps
– Seasonal extremes
• January & July
– BROAD
understanding of
temperature patterns
– Isotherm: line
connecting
points of equal
temperature
31
Global Temperature Patterns
• Primary controls on global
temperature
– Altitude
• Temperature decreases with
altitude
– Latitude
• Fundamental cause of
temperature variation
• Temperature with latitude
Figure 4-29 – average January temperature
– Land–Water contrasts
• Continents have higher
summer & lower winter temps
than oceans
– Ocean currents
• Cool currents push isotherms
equatorward; warm currents
push isotherms poleward
Figure 4-30 – average July temperature
Global Temperature Patterns
• Seasonal patterns
– Latitudinal shift in isotherms from one season to another
– More pronounced over continents than water and over high
latitudes than
low latitudes
Figure 4-31
Global Temperature Patterns
• Annual temperature range
– Difference in average temperature of warmest and
coldest months (usually Jan & July)
Figure 4-32
Global Warming and the
Greenhouse Effect
• Climate of Earth is becoming warmer, known as global warming
– Air temp increases when atmospheric gases trap longwave radiation
• Human-enhanced greenhouse effect
– Carbon dioxide main culprit
– Also methane, nitrous oxide, CFC’s
• Intergovermental Panel on Climate Change
Figure 4-33
Global Warming and the
Greenhouse Effect
• Relationship between carbon dioxide and temperature
Figure 4-35
Summary
• Temperature affects both living and nonliving aspects of Earth’s landscape
• Energy exists in many different forms, but cannot be created or destroyed
• Temperature is a measure of the amount of kinetic energy in the molecules
of a substance
• Temperature is measured on three primary scales
• The Sun is the primary source of energy for Earth’s atmosphere
• Electromagnetic radiation is classified by wavelength
• The Sun emits three important types of electromagnetic radiation: visible,
infrared, and ultraviolet
• Insolation refers to incoming solar radiation
• Radiation is the process by which electromagnetic radiation is emitted by an
object
• Radiation can undergo several processes, including absorption, reflection,
transmission, and scattering
• The greenhouse effect makes Earth able to support life
Summary
•
•
•
•
•
•
•
•
•
•
Conduction is the transfer of heat through molecular collision
Convection is a vertical transport of heat in a fluid
Advection is the horizontal transport of heat
Adiabatic cooling and warming processes do not release or absorb heat
The global radiation budget describes the latitudinal distribution of
temperature
Land surfaces heat and cool faster than water surfaces
Heat is transferred globally through atmospheric and oceanic circulations
The vertical temperature patterns in the atmosphere help describe vertical
circulations
Global warming is the observed warming of the atmosphere
Temperature and carbon dioxide show a close relationship