Download Lab: Absorption and Radiation by Land and Water

Name: ____________________________________________
Lab: Absorption and Radiation by Land and Water
Date: __________
Adapted from Exploration in Earth Science, The Physical Setting, United Publishing Company, Inc
Introduction: Approximately 70% of the Earth is covered by water. Water has a high specific heat, so it
heats and cools slowly. Land, on the other hand, has a low specific heat, so it heats and cools quickly.
Since land and water heat and cool unequally, this affects local and global weather patterns.
On a clear summer day, air heats up a lot over the land, but not so much over the water. The heated air
over the land becomes less dense and rises, while the more dense air over the water sinks. This causes a
“sea breeze” to blow onto the land. The opposite effect (“land breeze”) occurs at night.
Objective: You will be able to describe the comparative rates at which water and land surfaces
heat and cool.
Hypothesis:
Vocabulary:
Heat Equator -
Specific Heat -
Radiative Balance Procedure:
1. Fill one can half full with room temperature water.
2. Using a balance, determine the mass of the can and water.
3. Remove the can with the water from the balance.
4. Place an empty can on the balance. Carefully add soil to the empty can until the combined
mass of the can and soil is equal to the mass of the can and water.
5. Make sure that both thermometers are equal in temperature; otherwise ask for a new set of
thermometers. Place a thermometer in each can so that the bulb if the thermometer is just
below the can’s contents.
6. Allow the thermometers to reach room temperature. Enter that temperature in the TIME 0
section on your Data Table.
7. Place two cans under the heat lamp and adjust the lamp
so that both cans will receive equal energy.
8. Turn on the heat lamp and take temperature readings at
ONE minute intervals for a time period of ten minutes.
Record these temperature readings on your Data Table.
9. At the end of 10 minutes, TURN OFF the lamp and
remove it from the area next to the two cans. Continue
reading and recording of the thermometers, each
minute for ten more minutes.
10. Make a line graph show both sets of data on the same
set of axes. Use a different color or symbol for each
curve drawn. Label each line. Be sure to include a title
for your graph, make appropriate scales for each
variable, and label each axis appropriately.
Discussion Questions:
1. Which cup heated more rapidly?
2. Which cup cooled more rapidly?
3. Which is a better absorber and radiator of heat and energy, soil or water?
4. By 3:00pm on a summer day, would air be cooler over ocean water or over the nearby
land? Explain your answer.
5. Referring the Earth’s Heat Equator Diagram above, why does the heat equator for
January bend further into the Southern Hemisphere over the continents of South America
and Africa than it bends over the ocean areas?
Base your answers to the following questions based on the isotherm maps above, which show the average
monthly temperatures (°F) over a portion of Earth’s surface for January and July.
6. Compare what latitude the hottest average January temperatures occur at to the hottest
average July temperatures.
7. Explain why there is a smaller temperature change in the Southern Hemisphere than in
the Northern Hemisphere from January to July.
Conclusion: How do water and land surface differ in their abilities to absorb and radiate heat
energy?
Reading Comprehension: Read the article below on Sea Breezes and answer the questions that
follow (in complete sentences).
Sea Breezes Help Coast Stay Cool
By Chad Palmer, USATODAY.com
http://www.usatoday.com/weather/wseabrze.htm
A sunny, warm April morning with temperatures in the 70s begins a beautiful spring day in New Jersey.
As you and the family go on a picnic to take advantage of the great weather, a sudden chill roars through
the region and a stiff wind from the east quickly drops temperatures into the 40s. This often occurs near the
coast during early spring warm-ups. It is commonly known as a sea breeze.
How sea breezes form
An easy spring sea breeze can ruin a day at the beach, but during summer's hot days of summer, sea breezes
can bring welcome relief.
Sea breezes form because water heats up much slower than land. As the land heats up, it warms the air
close to the ground and the warmer, lighter air begins rising. Cool air over the ocean is heavier and more
dense than the warm air over land. The cool air nudges its way inland to replace the rising air, and can
create a strong wind across the ocean and on shore.
The bigger the temperature contrast between the air temperature inland and the water temperature, the
better chance of a sea breeze developing and the stronger it will be.
As air from over the ocean carries humidity inland, it joins the rising air and begins condensing to form
clouds as the air rises and cools. This is why you will often see a line of clouds a few miles inland on
afternoons when a sea breeze is blowing. The line of clouds is often called the "sea breeze front."
1. Why does a sea breeze form?
2. What makes a sea breeze more likely to form?
3. What is a sea breeze front?
4. Explain why we get land breezes at night.