Ch. 6 Review Questions

Describe the three main forms of clouds.

Cirriform is thin and wispy Cumuliform is puffy like cotton balls Stratiform has a thick, solid layer like a blanket

Describe the four main lifting mechanisms of air.

Convergent lifting - area of low pressure, gets the air to dew point, and possibly precipitation Frontal lifting - boundary between dissimilar air masses, cold air moves across the surface and hits warm air, boundary zone/collision zone creates lift Convection - heating at the surface, insolation throughout the day, warm air rises, late afternoon because heating will be most intense Orographic - topographic barrier create and force the air to rise

Why is evaporation a "cooling" process? Why is condensation a "warming" process?

Evaporation is a cooling process because when liquid turns to gas, it needs more energy, and so it has to take that energy from its surroundings. The energy is in the form of heat, and when the heat energy leaves with the evaporating liquid, the surroundings get cooler as a result. The formation of condensation is a warming process because it releases energy into the atmosphere that causes its temperature to increase. When condensations forms, water vapor condenses from a gas into a liquid. The liquid state requires less energy than the gas state. Condensation is the change from a vapor to a condensed state (solid or liquid). Evaporation is the change of a liquid to a gas.

What happens to the relative humidity of a parcel of air when the temperature decreases? Why?

If the temperature of the parcel of air decreases, the relative humidity increases. This is a KEY point. If you did not answer this correctly, you really should go back and review the explanation of relative humidity.

Describe the four principal types of fogs.

Radiation - valley fog Advection - coastal fog Upslope Evaporation - "steam" fog (warm air -> cool air)

What is the dew point temperature?

Temperature at saturation. Saturation is at 100% relative humidity.

Using the maps of average January and July precipitation (Figure 6-35), contrast and explain the seasonal rainfall patterns in central Africa.

While Central Africa receives relatively abundant rainfall year-round (or less than 10% variability), there are some distinct differences. During January, because of greater amounts of insolation in the Southern Hemisphere, the ITCZ and the STHs dip south, creating greater amounts of convectional heating and changes in the patterns of air pressure. As a result, the portions of this region south of the equator receive greater amounts of precipitation in January. Conversely, during July, the ITCZ and STHs shift north, creating greater amounts of precipitation northward of the equator in this region.

Describe and explain what is meant when we say that the relative humidity of the air is 50 percent.

the air is 50% of the way to saturation. also the air contains half of the max. possible water vapor at that temp. Relative humidity compares the amount of water vapor in the air to the amount of water vapor "capacity" of the air, and gives a percentage to describe how close the air is to saturation with water vapor. A relative humidity of 50 percent means that the air is "holding" one-half of the water vapor it is capable of holding at that given temperature. To make this easier to explain, I'll define relative humidity. A measure of how much water vapor is in the air compared to how much it can hold, given as a percentage.If it is at 50%, then there is 50% of the maximum amount of water vapor in the air that it can hold.