Homework 1 Solutions
(1) Let’s say that someone asks you to help them with some satellite data. They want to be able
to look at the evolution of surface temperature throughout the entire day (every hour) for a
remote desert location without any surface observations.
(a) What type of satellite orbit would you suggest they use, and why?
Answer: You would want to select a GOES satellite orbit, because they stay over the same
spot of the planet and therefore can take many images throughout the day, rather than just
two like the POES can.
(b) What type of satellite imagery would you suggest they use, and why?
Answer: You would want to select an Infrared (IR) type of imagery because it is very useful
at detecting the temperature of objects emitting radiation. Since it’s a desert, it’s probably
pretty clear throughout the day, which means we can easily observe the surface
temperature.
(2) Imagine you have a balloon that is unable to expand or contract. If that balloon is filled with
room temperature air and then put into a freezer …
(a) What happens to the temperature of the air in the balloon, and why?
Answer: It will decrease, because heat travels from warmer objects to colder objects, and
the rest of the freezer is cold, so the balloon will cool.
(b) What happens to the density of the air in the balloon, and why?
Answer: The density would have to stay the same, since the balloon’s volume is fixed, and
the mass stays the same.
(c) What happens to the pressure on the inside walls of the balloon, and why?
Answer: According to the ideal gas law, if the density stays the same, but the temperature
decreases, the pressure must also decrease. Another way to look at it is that the molecules
are moving slower, so they will exert less pressure.
(d) What happens to the speed of the molecules inside the balloon, and why?
Answer: Temperature is a measure of Kinetic Energy, which is proportional to velocity
squared. So if the temperature decreases, then KE decreases, which means the velocity
must decrease.
(3) Imagine the sun is shining strongly in northern Illinois, and that the wind is blowing from the
south the entire distance between Madison and northern Illinois. Describe in a paragraph the
different forms of heat transfer that are taking place, and how/where they are occurring.
Answer: The sun is transferring energy to the surface through radiation. As the surface
warms, it transfers heat to the neighboring air molecules through conduction. As that air
warms and becomes less dense than the air above it, it will rise and mix with that air,
transferring heat by convection. The south wind then transports heat towards Madison
through advection. (You must get at least three for full credit)
(4) For the following two station models, list the following: current temperature, dewpoint, full
pressure, wind direction and speed, cloud cover, and current weather. No explanation is
necessary.
Answer:
(1) Temperature: 55
Dewpoint: 47
Pressure: 999.8 (mb)
Wind: South at 15 knots
Clouds: Overcast
Weather: Light Rain
(2) Temperature: 95
Dewpoint: 87
Pressure: 1010.3 (mb)
Wind: Southeast at 15 knots
Clouds: Overcast
Weather: Thunderstorm (with rain)