Major Concepts in Climate
Change
Learner Outcomes: At the end
of this lecture you will be able to
• Describe major concepts related to climate
change and global warming.
• Define density, gradient, albedo, and
convection.
• Describe the difference between linear
and nonlinear.
Density
•
Density = MASS (grams)
VOLUME (cubic centimeters)
• Often expressed as g/cm3
• Usually as temperature increases, volume
increases
• As pressure increase, volume decreases
• Density is affected by temperature and pressure
What is convection?
• Convection is a physical process cause by
temperature and density gradients
• Hotter (less dense) material rises.
• As it rises it cools (becomes more dense)
and sinks
Gradient
• Slope or difference
• Moves energy
• Greater slope, faster velocity, flux or
movement
• Energy moves from high energy state to
low energy
– Temperature moves from high to low
– Salinity moves from high to low
How does energy travel?
• Form of a wave
• Wavelength (frequency)
• Electromagnetic spectrum
Electromagnetic Spectrum
What is the electromagnetric
spectrum?
• The wavelengths of light span an enormous range –
from fractions of a millimeter (for X-rays) to
kilometers (for radiowaves).
• Light waves travel at the speed of 300,000 km/sec.
• Visible light has wavelengths between 400 and 700
nanometers.
• The shorter wavelengths of ultraviolet (UV) light can
cause mutations and sunburns, but are generally
filtered out by the ozone layer.
Linear vs. Nonlinear
Y
X
Linear
Nonlinear
Linear vs. Nonlinear
• Linear -Fixed change in Y with change in
X
• Nonlinear (i.e. exponential)-change in Y
increases at constant percentage
• Exponential example: population
– Number of people added to population is not
constant, percentage of people added is
constant
“Sinks”
• A natural or artificial means of absorbing
or removing a substance or a form of
energy from a system.
• Reservoir for storing or accumulating
energy
• Heat Sink
• Carbon Sink
Albedo: Reflectivity
• Albedo is the degree to which object
reflects light (energy)
– Color (and temperature)
– Surface texture
– Dependent upon Angle
• Higher albedo surface will reflect more
energy
• Lower albedo surface will absorb more
energy
Albedo: Solar Zenith Angle
• Determined by the latitude, time of year,
and time of day.
• i.e. In the Northern Hemisphere, the sun
shines directly overhead at noon at the
Tropic of Cancer on the first day of
summer
Albedo:Solar Zenith Angle
Albedo of Different surfaces
Surface
Soil
Details
Albedo
Dark vs. Light (wet to dry) 0.05-0.40
Grass
Crops
Forests
Long vs. Short
Deciduous
Coniferous
0.16-0.26
0.18-0.25
0.15-0.20
0.05-0.15
Albedo of Different Objects
Surface
Water
Snow
Ice
Clouds
Details
Small zenith Angle
Large Zenith Angle
Old-Fresh
Sea
Glacier
Albedo
0.03-0.10
0.1-1.0
0.40-0.95
0.3-0.45
0.20-0.40
Thick
Thin
0.60-0.90
0.30-0.50
Feedback
• Positive-enhances effect
• Negative-decreases effect
Positive Feedback
• Snow and Keeping the Earth Cool
– Albedo of snow: high reflectivity
– High reflectivity, less energy
– Less energy, less heat
– Earth stays cool/cold
Feedback Mechanisms
• Feedback mechanism - when physical
processes in the earth-atmosphere system
further impact the initial change
• if the impact is such that the initial
perturbation is enhanced, then it is called a
positive feedback mechanism -->
• if the impact is such that the initial
perturbation is reduced, or weakened, then it
is called a negative feedback mechanism.
QOD
The albedo of snow would provide
A) A positive feedback to global warming
B) A negative feedback to global warming
C) Increased reflectivity
D) B and C