Deck 4: Atmospheric Humidity

Question 1

Which of the following will increase in a rising parcel of air?

A) saturation vapor pressure
B) relative humidity
C) mixing ratio
D) air temperature
E) none of the above

Answer 1

B

Question 2

If water vapor comprises 3.5 percent of an air parcel whose total pressure is 1000 mb,the water vapor pressure would be

A) 1035 mb.
B) 35 mb.
C) 350 mb.
D) 965 mb.

Answer 2

B

Question 3

When the air temperature increases,the saturation vapor pressure will

A) increase.
B) decrease.
C) remain the same.
D) vary over an increasingly broad range of values.

Answer 3

A

Question 4

Which of the following will increase the relative humidity in a home during the winter?

A) increasing the thermostat setting
B) lowering the temperature of the air inside the home
C) sealing the house against drafts
D) taking a shower and letting the air circulate through the home

Question 5

As the air temperature increases,the air's capacity for water vapor

A) increases.
B) decreases.
C) remains constant.
D) is unrelated to air temperature and can either increase or decrease.

Question 6

The total mass of water vapor stored in the atmosphere at any moment is about ____ of the world's supply of precipitation.

A) 1 day
B) 1 week
C) 1 month
D) 1 year

Question 7

If the amount of water vapor in the atmosphere remains constant,the humidity

A) cannot change.
B) must change.
C) might change,depending on which measure of humidity is used.
D) will only change if we're using absolute humidity as the measure of humidity.

Question 8

When the air temperature is below freezing,the saturation vapor pressure over water is

A) equal to zero.
B) less than the saturation vapor pressure over ice.
C) greater than the saturation vapor pressure over ice.
D) equal to the saturation vapor pressure over ice.

Question 9

The ratio of the mass of water vapor in a given volume (parcel)of air to the mass of the remaining dry air describes the

A) absolute humidity.
B) mixing ratio.
C) relative humidity.
D) dew point.

Question 10

A high water vapor pressure indicates

A) a relatively large number of water vapor molecules in the air.
B) a relatively small number of water vapor molecules in the air.
C) a relatively high rate of evaporation.
D) an abundant supply of condensation nuclei in the air.

Question 11

When the air is saturated,which of the following statements is NOT correct?

A) The air temperature equals the wet-bulb temperature.
B) The relative humidity is 100 percent.
C) The air temperature equals the dew point temperature.
D) An increase in temperature will cause condensation to occur.
E) The wet bulb temperature equals the dew point temperature.

Question 12

The maximum pressure that water vapor molecules would exert if the air were saturated is called the

A) absolute humidity.
B) boiling point.
C) mixing ratio.
D) none of the above

Question 13

If a glass of water was surrounded by saturated air,

A) the level of the water in the glass would slowly decrease.
B) the water's temperature would slowly increase.
C) the level of the water in the glass would not change.
D) the water's temperature would slowly decrease.

Question 14

If very cold air is brought indoors and warmed with no change in its moisture content,the saturation vapor pressure of this air will ____ and the relative humidity of this air will ____.

A) increase,increase
B) decrease,decrease
C) increase,decrease
D) decrease,increase

Question 15

Which of the following will decrease in a rising parcel of air?

A) relative humidity
B) absolute humidity
C) specific humidity
D) all of the above

Question 16

The Gulf Coast states are more humid in summer than the coastal areas of Southern California mainly because of the

A) higher air temperature in the Gulf States.
B) lower air temperature in Southern California.
C) higher water temperature in the Gulf of Mexico.
D) low relative humidity of the air over the Pacific Ocean.

Question 17

Evaporative coolers are primarily used in climates where the summers are

A) hot and humid.
B) hot and dry.
C) cold and humid.
D) cold and dry.

Question 18

The density of water vapor in a given parcel of air is expressed by the

A) absolute humidity.
B) relative humidity.
C) mixing ratio.
D) specific humidity.
E) saturation vapor pressure.

Question 19

If the air temperature increased,with no addition or removal of water vapor,the actual vapor pressure would

A) increase.
B) decrease.
C) stay the same.
D) become greater than the saturation vapor pressure.

Question 20

Ignoring the contributions of wind,a baseball would be expected to travel farther in warm,humid air because

A) water vapor helps to lift the baseball even higher.
B) water vapor sticks to baseballs.
C) water vapor is less dense than dry air.
D) none of the above

Question 21

As the difference between the air temperature and the dew point increases,the relative humidity

A) increases.
B) decreases.
C) remains constant at a value less than 100 percent.
D) remains constant and equal to 100 percent.

Question 22

If the air temperature remains constant,evaporating water into the air will ____ the dew point and ____ the relative humidity.

A) increase,increase
B) increase,decrease
C) decrease,increase
D) decrease,decrease

Question 23

At what time of day is the relative humidity normally at a minimum?

A) when the air temperature is highest
B) just before sunrise
C) about midnight
D) when the air temperature is lowest

Question 24

A sling psychrometer directly measures the relative humidity.

Question 25

Suppose the dew point of cold outside air is the same as the dew point of the air indoors.If the door is opened and cold air replaces some of the warm air,then the new relative humidity indoors would be

A) lower than before.
B) higher than before.
C) the same as before.
D) impossible to tell from the information given

Question 26

The relative humidity is often near 100 percent in the polar regions.

Question 27

Suppose it is snowing outside and the air is saturated.The air temperature and dew point are both 15°F,and the actual vapor pressure is 3 mb.If this air is brought indoors and warmed to 75°F,what would the relative humidity of this air be,assuming that its moisture content does not change? (The saturation vapor pressure at 75°F is 30 mb).

A) 5 percent
B) 10 percent
C) 30 percent
D) 50 percent
E) 100 percent

Question 28

Exhibit 4-1
The following four questions refer to the temperature and dew point data in the following cities:

Refer to Exhibit 4-1.Which city has the HIGHEST saturation vapor pressure?

A) City A
B) City B
C) City C
D) City D

Question 29

As the air temperature increases,with no addition of water vapor to the air,the relative humidity will

A) remain the same.
B) increase.
C) decrease.
D) increase until it becomes equal to the dew point temperature.

Question 30

Suppose saturated polar air has an air temperature and dew point of -10°C,and unsaturated desert air has an air temperature of 35°C and a dew point of 10°C.The desert air contains ____ water vapor and has a ____ relative humidity than the polar air.

A) more,lower
B) more,higher
C) less,lower
D) less,higher

Question 31

If the air temperature in a room is 70°F,the saturation vapor pressure is 25 mb,the dew point temperature is 45°F,and the actual vapor pressure is 10 mb,then the relative humidity must be near ____ percent.

A) 15
B) 20
C) 35
D) 40

Question 32

The time of day when the relative humidity reaches a maximum value is usually

A) at the time when the air temperature is highest.
B) in the middle of the afternoon.
C) at the time when the air temperature is lowest.
D) just before sunrise.
E) about midnight.

Question 33

The temperature at which water boils depends mainly on

A) air temperature
B) relative humidity
C) air pressure
D) air density
E) the specific heat of air

Question 34

With which set of conditions below would you expect wet laundry hanging outdoors on a clothesline to dry most quickly?

A) I
B) II
C) III
D) IV
E) V

Question 35

Exhibit 4-1
The following four questions refer to the temperature and dew point data in the following cities:

Refer to Exhibit 4-1.Which city has the LEAST amount of water vapor in the air?

A) City A
B) City B
C) City C
D) City D

Question 36

The dew point temperature is a measure of the total amount of water vapor in the air.

Question 37

Exhibit 4-1
The following four questions refer to the temperature and dew point data in the following cities:

Refer to Exhibit 4-1.Which city has the GREATEST amount of water vapor in the air?

A) City A
B) City B
C) City C
D) City D

Question 38

Exhibit 4-1
The following four questions refer to the temperature and dew point data in the following cities:

Refer to Exhibit 4-1.Which city has the highest relative humidity?

A) City A
B) City B
C) City C
D) City D

Question 39

The main reason why vegetables take longer to cook in boiling water at high altitudes is because

A) water boils at a higher temperature with higher altitude.
B) the temperature of the boiling water decreases with increasing altitude.
C) there is less oxygen in the air at high altitude.
D) saturation vapor pressure decreases with increasing altitude.

Question 40

The percentage of water vapor present in the air compared to that required for saturation is the

A) mixing ratio.
B) absolute humidity.
C) dew point.
D) relative humidity.
E) specific humidity.

Question 41

As the air temperature increases,with no addition of water vapor to the air,the dew point will

A) remain the same.
B) increase.
C) decrease.
D) increase and become equal to the air temperature.

Question 42

Which of the following is the BEST indicator of the actual amount of water vapor in the air?

A) air temperature
B) saturatin vapor pressure
C) relative humidity
D) dew point temperature

Question 43

Bespectacled people know that when entering a warm building after being outdoors in subfreezing temperatures,condensation occurs on the lenses of their glasses.Why doesn't condensation occur on the lenses when they go outside after a lengthy stay inside the warm building?

Question 44

Which of the following statements is not correct?

A) The length of human hair changes as the relative humidity changes.
B) During the winter,low relative humidity can irritate the mucus membranes in the nose and throat.
C) The relative humidity is a measure of the air's actual water vapor content.
D) A change in the air temperature can change the relative humidity.

Question 45

The lowest temperature that can be attained by evaporating water into the air is known as the

A) heat index.
B) minimum temperature.
C) wet-bulb temperature.
D) frost point.
E) wind chill temperature.

Question 46

This instrument uses wet-bulb and dry-bulb temperature to obtain relative humidity:

A) infrared hygrometer
B) sling psychrometer
C) hair hygrometer
D) electrical hygrometer

Question 47

In terms of the air temperature and water vapor content,explain how the relative humidity normally changes during the course of a 24-hour day.

Question 48

In a blinding snowstorm in Vermont,the air temperature and dew-point temperature are both 30°F.Meanwhile,under clear skies in Arizona,the air temperature is 85°F and the dew point temperature is 38°F.From this information,you could conclude

A) there is more water vapor in the air in Arizona.
B) there is more water vapor in the Vermont snowstorm.
C) the same amount of water vapor is found in the air in Vermont and Arizona.
D) Vermont and Arizona are both located next to the ocean.

Question 49

In order to reduce evaporation and conserve water,do you think it would be better to water a lawn in the early morning or early evening?

Question 50

Would lowering the temperature in your home during the winter cause the relative humidity to increase or decrease? Why?

Question 51

Explain why,at temperatures below freezing,the saturation vapor pressure over water is greater than the saturation vapor pressure over ice.

Question 52

The temperature to which air must be cooled in order to become saturated is the

A) minimum temperature.
B) dew point temperature.
C) wet-bulb temperature.
D) freezing point.

Question 53

The instrument that measures humidity by measuring the amount of radiant energy absorbed by water vapor is the

A) electrical hygrometer.
B) infrared hygrometer.
C) sling psychrometer.
D) hair hygrometer.
E) dew cell.

Question 54

What is meant by the terms water vapor saturation and saturation vapor pressure? Why does the saturation vapor pressure increase with increasing air temperature?

Question 55

With the aid of a figure,illustrate and describe the circulation of water in the atmosphere (the hydrologic cycle).

Question 56

At 40°F,the atmosphere is saturated with water vapor.If the air temperature increases to 60°F,with no addition or removal of water vapor,one may conclude that the dew point is about

A) 20°F.
B) 40°F.
C) 60°F.
D) 100°F.

Question 57

Explain why the dew point temperature provides a better indication of the actual amount of water vapor in the air than the relative humidity.

Question 58

What physiological effects might you experience during very humid and very dry conditions?

Question 59

Using the concept of supercooled water,explain why ice cubes sometimes feel "sticky" when taking them out of the freezer.

Question 60

Nighttime temperatures rarely drop below the dew point temperature because

A) the dew will absorb all the heat.
B) saturation vapor pressures always increase at night.
C) at saturation,latent heat of condensation is released into the air.
D) b and c

Question 61

An enterprising travel agent trying to sell you a summer vacation package to Phoenix,Arizona,claims that the summertime relative humidity is above 90 percent.Can this be true? Explain.

Question 62

Would hazy conditions generally indicate dry or humid conditions?

Question 63

How could you heat air without decreasing its relative humidity?

Question 64

Describe how a sling psychrometer can be used to determine the relative humidity or dew point.

Question 65

Why is perspiration an effective means of cooling human skin?