Chapter 6 Concepts

(Page 153) Briefly describe the three main forms of clouds.

(1)Cirriform Clouds-Thin and wispy and composed of ice crystals rather than water droplets. (2)Stratiform Clouds-Grayish sheets that cover most or all of the sky, rarely broken up into individual cloud units. (3) Cumuliform clouds-Horizontal extent but often billowing upward to great heights.

What is by the latent heat of condensation? Latent heat of evaporation?

-Latent heat of condensation is energy released when water vapor condenses to form liquid droplets. -If the water vapor condenses back to a liquid or solid phase onto a surface, the latent energy absorbed during evaporation is released as sensible heat onto the surface.

(Page 147) Describe the conditions associated with relatively high rates of evaporation, and the conditions associated with relatively low rates of evaporation.

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(Page 151) Which cooling process in the atmosphere is responsible for the formation of most clouds (and nearly all cloud that produce precipitation)?

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What is the general relationship of precipitation variability to average annual precipitation?

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What is the relationship of the dew point temperature of a parcel of air to its lifting condensation level?

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(Page 164) Describe the four main lifting mechanisms of air: convective, orographic, frontal and convergent.

1. convective - warm air rising from surface 2. orographic - air ascending an upslope (mtn.) is cooled to dew pt. 3. frontal - warmer air is forced to rise over cooler air and clouds form & precipitation may occur. 4. convergent - general uplift when air converges (meets together and goes up)

What is meant by surface tension of water?

A thin "skin" of molecules forming on the surface of liquid water, causing it to "bead" (stick)---b/c of its electrical polarity, liquid water molecules tend to stick together, giving water extremely high surface tension- a thin "skin" of molecules forms on the surface of liquid water.

(Page 151) Under what circumstances can air become supersaturated?

Air is supersaturated when it has absorbed all the moisture possible at that temperature. By the way, hot air can hold more moisture than cold air, which is why it is called relative humidity.

What determines the water vapor capacity of air?

Atmospheric pressure.

How and where does dew form?

Dew originates from terrestrial radiation. Night time radiation cools objects at earth's surface and the adjacent air is in turn cooled by conduction. If the air is cooled enough to reach saturation, tiny beads of water collect on the cold surface of the object.

Identify the four families of clouds.

High, Middle, Low and Vertical.

Describe what happens to the density of water as it freezes.

It becomes less dense than liquid water because water expands as it approaches its freezing point.---Density decreases as it freezes. Ice floats in water b/c it's less dense.

Explain sensible temperature.

Key Term

What are supercooled water droplets.

Key Term

(Page 148) What is absolute humidity? Specific Humudity?

Key Terms

(Page 161) Briefly describe the following kinds of precipitation:Rain, snow, hail.

Key Terms

Contrast the dry adiabatic rate and a saturated adiabatic rate.

Key Terms

How do phase changes of water entail the exchange of energy? (in other words explain latent heat.)

Latent heat is the energy released or absorbed by a body or a thermodynamic system during a constant-temperature process. A typical example is a change of state of matter, meaning a phase transition such as the melting of ice or the boiling of water.

(Page 145) Briefly define the following the terms; Evaporation, condensation, sublimation.

Look at key terms

(Page 142) Briefly describe how water moved through the hydrologic cycle.

Moisture leaves earth's surface as a gas and returns as a liquid or solid.--- water from oceans EVAPORATES in air, CONDENSES to liquid (or solid), and returns to Earth as precipitation.

Describe the four principal types of fog.

Radiation Fog-When ground loses heat through radiation, usually at night. Heat passes through the lowest layer of air and into the higher areas. The air closest to the ground cools as heat flows conductively from it to the relatively cool ground (2) Advection Fog- Develops when warm, moist air moves horizontally over a cold surface, such as snow covered ground or a cold ocean current. Air from sea to land is most common. (3) Upslope Fog-Created by adiabatic cooking when humid air climbs a topographic slope.

Are stratus clouds associated with stable or unstable air?

Stable air

What is Capillarity?

Surfaced tension combined with adhesion allowing water to climb upward in narrow openings. Confined, water can sometimes climb upward in narrow openings.

What is evapotranspiration?

The combined process of Evaporation entering the air from land sources.--

what is meant by saturation vapor pressure?

The maximum possible vapor pressure at a given temperature.

What happens to the relative humidity of an unsaturated parcel of air as it rises? why?

The relative humidity drops. This is because the temperature for the parcel of air is cold and wet which leaves enough room for some water vapor, but not a lot. It cools at the relatively steady rate of 10 degrees celcius per 1000 meters, Known as dry adiabatic.---when temp decreases, relative humidity increases when temp increases, relative humidity decreases

What is the dew point temperature.

The temperature at which saturation is reached.

What is the hydrogen bond between water molecules?

They are weak covalent bonds that tend to hold themselves (cohesion) toward each other where the negatively charged oxygen sides with a positively charged hydrogen.

What conditions make a parcel of air unstable?

To be "unstable", the lowest layers of an air mass must be so warm and/or humid that, if some of the air rises, then that air parcel is warmer than its environment, and so it continues to rise. This is called moist convection. -(Dry Adiabatic Rate?)

What is meant by the vapor pressure of water in the atmosphere?

Total atmospheric pressure is simply the sum of the pressures exerted by all of the individual gases in the atmosphere. FYI: The presence of water vapor in our atmosphere plays a large role in determining the weather. Clouds and precipitation occur as a result of the phase change that occurs when water vapor condenses into liquid water.

(Page 157) What is the difference between stable air and unstable air?

Unstable air, if lifted, will rise by itself without any forcing. Stable air, if lifted, will tend to sink back down.

(Page 167) What is an isohyet?

a line joining points of equal numerical value of precipitation.

What is a rain shadow?

area of low rainfall of the leeward side of a mtn range. (dry)

Explain the role of condensation nuclei to the condensation process.

condensation nuclei serves as a surface (tiny particles like dust, smoke, pollen) collection center for water molecules during condensation.

What is meant by the term precipitation variability?

expected departure from average annual precipitation in any given year

(Page 171) What are some of the circumstances that cause acid rain?

high concentration of sulfuric and nitric acids in the atmosphere. (smokestacks, vehicle exhaust)

How is hail related to atmosphere instability?

highly unstable air and strong vertical air currents with warmer air on bottom and cooler air on top is needed to produce hail.

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.