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AnnouncementsPlease check your yearly
average in this class.
If you are below 70 for the year, please come and see
me ASAP!
There are only two more grades remaining!
Assignments For This Six-Weeks Date Issued Date Due
Lab – Air Masses, the Mid-Latitude Cyclones, and Weather Maps 4/20 4/25
Lab Quiz - Air Masses, the Middle-Latitude Cyclone, and Weather Maps 5/3 5/3
Lab – Weather Maps 5/4 5/6
Lab - National Weather Service Southern Regional Headquarters Local Weather
Information5/6 5/6
Test 10 5/10 5/10
Lab – Climate Change 5/13 ??
Human Impact on Global Climate Humans have been modifying the Earth’s environment over extensive areas for thousands
of years.
The use of fire changes the environment.
Overgrazing of marginal lands can cause changes as well.
Most hypotheses of climatic change are to some degree
controversial.
Global WarmingWater vapor and
carbon dioxide absorb heat and are largely responsible for the
“greenhouse effect” of the atmosphere.
Burning fossil fuels has added great quantities
of carbon dioxide to the atmosphere.
The Atmospheric Response It is a fact that global temperatures have increased.
The balance of evidence suggests a human influence on global climate change.
Our globally-averaged surface temperature is projected to increase by 34 to 42ºF by the year 2100.
Average global temperature variations 1860–2006
The left half of the graph shows global temperature
changes for the 20th Century. The right half shows
projected global warming in different emissions scenarios. The shaded zone adjacent to each colored line shows the uncertainty range for each
scenario. The basis for comparison (0.0 on the
vertical axis) is the global average for the period 1980-
1999. The orange line represents the scenario in which CO2 concentrations were held constant at the values for the year 2000.
The Atmospheric Response
Atmospheric trace gases like methane, nitrous
oxide, and certain chlorofluorocarbons,
absorb wavelengths of outgoing Earth radiation.
Taken together, their warming effects may be nearly as great as carbon
dioxide.
Climate-Feedback Mechanisms Climate is a very complex
interactive physical system.
Thus, when any component of the climate
system is altered, scientists must consider
many possible outcomes.These possible outcomes
are called climate feedback mechanisms.
Climate-Feedback Mechanisms So far the climate-feedback
mechanisms we discussed have magnified the temperature rise caused by the buildup of carbon
dioxide.Because these effects reinforce
the initial change, they are called positive-feedback mechanisms.However, other effects must be classified as negative-feedback
mechanisms because they produce results that are just the
opposite of the initial change and tend to offset it .
Human-generated aerosols are concentrated near the areas that
produce them. Because aerosols reduce the amount of solar energy available to
the climate system, thay have a net cooling effect. Here we see a dense
blanket of pollution moving away from the coast of China. the plume is about
120 miles wide and 360 mile long.
Some Possible Consequences of Global Warming
Global warming can alter the distribution of the world’s water
resources and can effect the productivity of agricultural regions.
It can cause a rise in global mean sea level.
By changing weather patterns, global warming could cause a
higher frequency and intensity of hurricanes.
It can cause shifts in the paths of large-scale cyclonic storms.
Global warming could also cause changes in frequency and intensity
of heat waves and droughts.