MET 101 Chapter 6

If this air rises as saturated air from 1000 mb, determine its temperature at 500 mb by following the dashed, curved blue saturated adiabatic lapse rate line passing through the starting point, up to 500 mb. At 500 mb, the saturated air parcel's temperature is approximately ________ °C.

-15

Continue the ascent to 500 mb. The air parcel temperature is now approximately ________ °C.

-27

If this air rises as unsaturated (dry) air from 1000 mb, determine its temperature at 500 mb by following the solid, straight green dry adiabatic lapse rate line passing through the starting point, up to 500 mb. At 500 mb, the temperature of the unsaturated air parcel is about ________ °C.

-35

If unsaturated (clear) air ascends 1000 m in the atmosphere, it will expand and its temperature will lower about ______ Celsius degrees. (The information in Chapter 5 of the text may also be helpful.)

10

If unsaturated air descends 1000 meters, it will compress and its temperature will ______ about 10 Celsius degrees.

10

Throughout this saturated portion of the ascent, the relative humidity of the air parcel is ________.

100%

Assume that all the water that condensed (or deposited) during the ascent was immediately lost as precipitation from the parcel. Therefore, if the air parcel at 500 mb begins to descend, it will experience warming by compression and immediately become an unsaturated parcel. As the parcel sinks back to the 1000-mb level, it will warm at the dry adiabatic lapse rate, as shown by following the dry adiabatic lapse rate line down from the point at 500 mb. When it arrives back at 1000 mb, its temperature is ________ °C.

27

Above the influence of the overrunning warm air from frontal advance, the saturated rising air rate can be determined as well. The Oakland rawinsonde text data provided the following: at 819 mb, the altitude and temperature were 1804 m and 7.4 °C, respectively. The level where the air ceases to be saturated is about 760 mb. The text data provides that level as 758 mb with an altitude of 2438 m and a temperature of 2.8 °C. Using these altitudes and temperatures as above, calculation provides an equivalent lapse rate of 7.3 C° per kilometer. The average lapse rate of saturated rising air in the atmosphere is approximately 6 C° per km. This calculated lapse rate value is ________ the average saturated adiabatic lapse rate.

About a degree from

The converging air in the several-state area centered on the L was forcing rising motion. Therefore, we ________ rising motions would be producing clouds in the Green Bay area.

Can be confident

Once you have a cloud in the bottle, squeeze the bottle to make the cloud disappear. The cloud disappears when the air temperature is raised by ________. The change in temperature results in evaporation of the cloud droplets.

Compression

Most clouds in the atmosphere form in a similar way as the cloud in the bottle. With the temperature change due to expansion, some of the water vapor in the saturated air must ________, thereby forming cloud droplets.

Condense

Referring back to Chapter 2's figure of the atmosphere's average vertical temperature profile, the stratosphere is

Conditionally stable

Wind directions in the several-state area including Green Bay, centered on the L in southwestern Indiana, were generally ________, as expected with the hand-twist model of a Low.

Counterclockwise

Air pressure in the open atmosphere always decreases with an increase in altitude. This happens because air pressure is determined by the weight of the overlying air. Air rising through the atmosphere expands as the pressure acting on it lowers and, in turn, its temperature ________.

Decrease

The cloud forms when the pressure acting on the saturated air lowered and the temperature ________.

Decrease

The expansion of air that occurred when the bottle was allowed to return to its original shape and volume was accompanied by a(n) ________ in the temperature of air inside the bottle.

Decrease

These observations indicate that when air is compressed, its temperature increases, and when air expands, its temperature ________.

Decrease

Air that is saturated with water vapor has a relative humidity of 100 %. If that air is heated without adding or removing water vapor, the relative humidity

Decreases

Air rising from the surface above Oakland cooled, and at about 845 mb, its temperature and dewpoint ________ become equal.

Did

In general, where precipitation was indicated by radar shadings across the map, sky cover conditions in station models near the shadings ________ display varying degrees of cloudiness. (Of course, cloud development can lead to precipitation but not all clouds precipitate! Several stations in the south-central U.S. had varying degrees of cloudiness without precipitation.)

Did

Recall that, based on the reported sky conditions, Oakland ________ have saturated atmospheric conditions and clouds above the ground. The saturated conditions were more extensive than the calculated layer above, but were complicated by horizontal atmospheric motions as well as the vertical.

Did

Station models showing sky cover conditions from Iowa eastward to New England ________ indicate that rising motions due to the low-pressure center and frontal boundaries across the area were also leading to cloud formation with rising air.

Did

The plotted temperatures were equal to, or very nearly so, the dewpoints from 930 mb up to about 580 mb. These equal temperature-dewpoint conditions ________ strongly indicate there was a layer of clouds over the Green Bay area.

Did

The rising air above Green Bay cooled, and at about 930 mb, its temperature and dewpoint ________ become equal.

Did

This sky cover condition confirmed that saturated air ________ exist aloft over Green Bay at that time.

Did

Generally, high pressure areas in the atmosphere tend to be clear because air in them experiences ________ motion. Low pressure areas tend to have clouds because air in them experiences motion in the reverse direction.

Downward

The frontal symbol on the map indicated that, at map time, the front was moving toward the ________.

East

Unstable air ______ vertical motion, convection, and cloud development.

Enhances

Begin once again with unsaturated air at 17 °C at 1000 mb. Because it is unsaturated, its relative humidity initially is ________ 100%.

Equal to

The lapse rate of unsaturated rising air in the atmosphere is theoretically 9.86 C° per km. This calculated lapse rate value in the actual atmosphere in this case was ________ the unsaturated adiabatic lapse rate. Unsaturated rising air really does follow an adiabatic process!

Essentially the same as

Air forced to rise above Green Bay would

Expand and cool

Air, rising over the upward-sloping, warm-frontal surface, moved aloft where it ________.

Expanded and cooled

If air is cooled until it reaches saturation at a temperature that is below 0 °C (32 °F), the air temperature has reached the

Frost point

If the container in the preceding question is warmed about 10 Celsius degrees (18 Fahrenheit degrees) and left at the new temperature until the air above the water surface again becomes saturated with water vapor, the concentration of water vapor will be about ______ what it was at the lower temperature.

Half

This temperature is ________ the temperature achieved by the unsaturated parcel that ascended dry adiabatically the entire way to 500 mb in item 1.

Higher than

As long as there is no addition or removal of water vapor, the relative humidity of unsaturated (clear) air rises as the air temperature falls. Hence, on a clear, calm day, the relative humidity is ______ near sunrise, the coldest time of day.

Highest

Air sinking in the atmosphere is compressed as the air pressure acting on it increases, and its temperature ________.

Increase

Compressing the air by squeezing the bottle was accompanied by a(n) ________ in the temperature of air inside the bottle.

Increase

The relative humidity of this air parcel is now ________ what it was when it began its journey at 1000 mb.

Less than

If condensation was occurring during the ascent from 800 mb to 500 mb, the air parcel would have ________ water vapor during the ascent.

Lost

Saturated (cloudy) air expands and cools as it ascends in the atmosphere (just as unsaturated air). As cloudy air rises, water vapor continually condenses as water droplets (or deposits as ice crystals) and latent heat is released to the atmosphere. Hence, ascending saturated (cloudy) air cools at a ______ rate than does ascending unsaturated (clear) air. (See also Chapter 5.)

Lower

At 500 mb, the temperature of the unsaturated air parcel is ________ the temperature of the saturated air parcel.

Lower than

This parcel's final temperature is ________ its beginning temperature when it was initially at 1000 mb.

Lower than

This comparison demonstrates that rising unsaturated, clear air cools ________ than rising saturated, cloudy air over the same pressure change.

More

The Green Bay station model showed the cloud cover at map time as ________.

Partly cloudy

Bands of light gray shading that indicate large water vapor content flows into hurricanes, thunderstorms and winter storms seen in water vapor imagery are called

Plumes

The change from the initial parcel temperature to the final parcel temperature at the 1000-mb level was caused by condensation (or deposition) which ________ latent heat.

Releases

As the air continues to rise, it will follow a ________ adiabatic lapse rate line.

Saturated

As this air rises, assume it becomes saturated at 800 mb. Being unsaturated from 1000 mb to 800 mb, it will follow a ________ adiabatic lapse rate line.

Saturated

Becoming saturated at 800 mb, its relative humidity is now _____ 100%

Saturated

A sealed container with liquid water in the bottom was left standing at a constant temperature until the air above the water surface became saturated with water vapor. The resulting pressure exerted by the water vapor is known as the ______ vapor pressure. The resulting vapor pressure value is unique to that particular temperature.

Saturation

It can be inferred from this investigation that in the open atmosphere where it is cloudy, air is generally ________ and cooling. Where the atmosphere is clear, the air is generally moving in the opposite direction.

Sinking

Air is ______ if air parcels tend to remain at the same altitude or, if displaced vertically, tend to return to their original altitude. The other condition occurs if, once displaced vertically, air parcels continue to move away from their original altitude.

Stable

The temperature profile from the surface up to about 890 mb over Oakland was parallel to the ________ adiabatic lapse rate line printed on the diagram. This was evidence of surface air moving upward and cooling by expansion at the unsaturated adiabatic lapse rate.

Straight, solid, green day

Water is continually cycled from one reservoir to another in the global hydrologic cycle. The process whereby liquid water vaporizes into the atmosphere is known as evaporation and the process whereby ice or snow vaporizes into the atmosphere without first becoming liquid is known as

Sublimation

The water vapor in air exerts a pressure, called vapor pressure, as though it were the only gaseous constituent present. That is, water vapor exerts a pressure that is not affected by the pressures exerted by other gases present. This is described in Dalton's law which states that a mixture of gases exerts a total pressure that is the ______ of the pressures exerted by each constituent gas.

Sum

Just west of the central California coast, the front nearest the coast was a ________ front.

Warm

Furthermore, the presence and shadings of radar returns scattered near Green Bay indicated that precipitation ________ occurring in this general area. Precipitation results from cloud formation and droplet growth processes.

Was

Green Bay, in eastern Wisconsin, was located to the north of the low-pressure center. The temperature and dewpoint at Green Bay at map time were 63 °F and 58 °F, respectively. Because the temperature and dewpoint at the surface were not equal, it indicated the air at the surface in Green Bay ________ saturated.

Was

On the Stüve diagram, the bold irregular curve to the right is the temperature profile while the bold curve to the left is the dewpoint profile. Where the curves are superimposed, the temperatures and dewpoints are equal. The separation of the temperature and dewpoint values at and near the surface indicates that the surface air ________ saturated.

Was

The air over Green Bay at 930 mb ________ saturated.

Was

The air over the Oakland area at 845 mb therefore ________ saturated.

Was

These conditions associated with Oakland all imply that the upper air over the area ________ rising.

Was

Oakland's Stüve diagram showed by the separation of the temperature and dewpoint values very near the surface that the surface air ________ saturated.

Was not

Oakland's temperature and dewpoint were given in the San Francisco station model as 64 °F and 49 °F, respectively. This tells us the air at the surface in Oakland/San Francisco area ________ saturated.

Was not

The Stüve diagram showed by the separation of the temperature and dewpoint values at the surface and above, that the surface air ________ saturated. This was confirmed by the Figure 2 values of the Oakland surface temperature and dewpoint.

Was not

Oakland/San Francisco's station model reported that clouds ________ located above Oakland. This positioning suggested that the upper air over Oakland had been lifted over the approaching frontal surface.

Were

As a general rule, the heaviest precipitation falls on the ______ slopes of a mountain range.

Windward