Download - Chapter 4: Insolation and Temperature
Chapter 4: Insolation and Temperature
The Impact of Temperature on the Landscape
• All living things influenced by temperature
• Adaptation to temperature extremes
• Temperature affects human-built 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
• 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
Figure 4-4
• Insolation– Incoming solar radiation– Shortwave energy
• Terrestrial Energy– Longwave
energy– “Earth’s”
energy
Energy, Heat, and Temperature
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– Earth radiation held
in by atmosphere– Atmospheric blanket
Figures 4-11 & 4-12
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
13
Radiation, Conduction & Convection Operating Simultaneously
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
18
• Earth does not distribute heat evenly through space & time– Cause of weather and climate
The Heating of the Atmosphere: Global Energy Budget
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 4-20
Figure 3-4
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
• 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
Figure 4-26
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
31
• Global temperature maps– Seasonal extremes
• January & July– BROAD
understanding of temperature patterns
– Isotherm: line connecting points of equal temperature
Global Temperature
Patterns
Global Temperature Patterns
• Primary controls on global temperature– Altitude
• Temperature decreases with altitude
– Latitude• Fundamental cause of
temperature variation• Temperature with latitude
– 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 4-29 – average January temperature
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 ChangeFigure 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