Physics 140:
Greenhouse
Effect
Spring 2008
Homework #4 - Due Wednesday, April 2, 2008
(1) (3 pts) By studying ice cores drilled in Antarctica, it is possible
to study the climate of the distant past. If the average thickness of an
annual layer is 8.75 millimeters, about how many years are covered by
the climate record of a 3-kilometer-long ice core? Show your work.
(2) (5 pts) Determine which of the following are feedback loops, and
which are not. For the feedback loops, determine which are positive and
which are negative. Briefly describe your reasoning for each.
(a) Increase in global temperature » melting of Arctic permafrost
» release of trapped methane into the atmosphere » increase
in global temperature.
(b) Increase in global temperature » reduced use of fossil fuel
for space heating » decrease of carbon dioxide released to
atmosphere » decrease in global temperature.
(c) Increase in global temperature » alarm about global warming
» conservation efforts that reduce use of fossil fuel »
decrease of carbon dioxide released to atmosphere » decrease in
global temperature.
(d) Increase in atmospheric carbon dioxide concentration »
increase in plant growth due to carbon dioxide fertilization effect
» decrease of atmospheric carbon dioxide concentration.
(e) Decrease in solar output due to change in sunspot activity »
decrease in global temperature » increased reflectivity of the
earth due to increased ice area.
(3) (3 pts) Water is to be added to a water tank whose base area is 120
square feet so that the water level rises by 10 inches. About how many
gallons must be added to the tank? (Recall that one gallon = 231 cubic
inches). Show your work.
(4) (3 pts) Consider a water tank whose base area is 120 square feet,
filled with water at a temperature of 20 C to a depth of 10 feet. If
the temperature of the entire tank of water is raised by 10 C, does the
water level in the tank rise, fall or remain the same? By how much, in
inches? Show your work. Assume the basal area of the tank does not
change with temperature, and that the volume thermal expansion
coefficient of water beta
= 0.000250 / °C (as a
reminder of the definition of beta, (Delta V)/V = beta (Delta T), where
V is the volume and T is the temperature). Show your work.
(5) (6 pts) Search on the Internet for an article or web page
describing a deadly heat wave (not including the ones mentioned in the
lecture note). Write a brief summary of the location, the
duration,
the temperatures reached and the death toll.
Attach a
printout of the article or web page with the relevant information
highlighted.