Homework #5
Student ID: 111000447
Name: Geunuk Na
Question 1: During a summer visit to New Orleans, you stay in an air conditioned motel. One
afternoon, you put on your sunglasses, step outside, and within no time your glasses are
“fogged up.” Explain what has caused this.
Answer: As I stayed inside an air conditioned motel, the temperature of my glasses is significantly
lower. When I put the glasses outside, the air is relatively warmer and the glasses can be treated
as cooling surface. In this type of situation, the air from the cooling surface mixes up with the
surrounding warm air and makes it as cool by lowering its dew point. As a result, an advection fog
is produced. Hence, my glasses start cooling the air adjacent to it and lowering its dew point. As
a result, an advection fog occurs. Thus, immediately my glasses will be fogged up.
Question 2:The air temperature during the night cools to the dew point in a
deep layer, producing fog. Before the fog formed, the air temperature cooled each hour
about 2°C. After the fog formed, the air temperature cooled by only 0.5°C each hour. Give
two reasons why the air cooled more slowly after the fog formed.
Answer: The dew point temperature is a temperature at which the air is saturated with water
vapor. The dew point temperature is 60 to 70 degrees Fahrenheit and 16 to 21 degrees
centigrade.
If the cool air passes over a warm area, then that leads to form fog. In fog, the humidity
percentage is high, so the amount of water vapor is also high. The air cools in nighttime with a
constant before and after forming fog.
The air cooled 3 degrees of Fahrenheit before forming a fog, because the air is saturated at the
dew point. The air cools 1 degree of Fahrenheit after fog forming of fog, because the water vapor
takes more time to cool.
Question 3: On a winter night, the air temperature cooled to the dew point and fog formed.
Before the formation of fog, the dew point remained almost constant. After the fog formed,
the dew point began to decrease. Explain why.
Answer: Dew point remains constant before the fog formation, because the air is unsaturated.
Hence, no condensation takes place. Once the fog is formed the air becomes saturated and
condensation takes place. The fog is composed of liquid water drops. Dew point temperature
measures the amount of water vapor in the air. When the fog is formed the vapor is converted into
liquid decreasing the water vapor content in the air. Therefore the dew point decreases when the
fog is formed.