Physical Science
Explain why warm air rises and cools as it expands.
Warm air is less dense than cooler air, so it rises. While rising, it expands by pushing apart the air around it by doing work. It gets the energy to do this work from the temperature of the gas, and by doing so it cools the gas.
Name ways in which thermal energy in air can be increased.
solar radiation, moisture condensation, conduction from warm ground, compression of the air
Relative humidity - the amount of water vapor in the air compared to the maximum amount able to be in the air at that specific temperature - is dependent on
temperature
What factors are responsible for condensation?
the ambient temperature at or below the dew point; cloud condensation nuclei
Are clouds that have vertical development characteristic of stable air, stationary air, unstable air, or dry air?
unstable air
What is a temperature inversion? Give one location where these inversions often occur.
when air temperature increases with altitude; Los Angeles
What is an adiabatic process?
when heat transfer is zero
Does condensation occur more readily at high temperatures or low temperatures? Explain.
Low temperatures, slow moving water molecules stick together when they collide
When water vapor condenses to liquid water, is heat absorbed or released?
released
How do clouds form?
A parcel of air cools, the air becomes saturated, and condensation of cloud drops begins.
Name the cloud group to which each of the following cloud types belongs: (a) altocumulus, (b) cirrostratus, (c) nimbostratus, and (d) cumulus clouds.
(a) middle clouds, (b) high clouds (c) low clouds, and (d) clouds having vertical development
Name the cloud form associated with (a) the hazy shade of winter, (b) a mackerel sky, (c) floating cotton, and (d) snowfall.
(a) stratus, (b) cirrocumulus, (c) cumulus, and (d) nimbostratus
Differentiate between a cold front and a warm front.
A warm front is when warm air moves into a cold air mass; a cold front is when cold air moves into a warm air mass.
Explain how a convection cycle is generated.
Air is warmed near the ground, rises, and cools, becomes denser than the surrounding air, then sinks back to the ground again.
Why does relative humidity increase at night?
Air temperature decreases at night, this decreases the maximum capacity for water vapor in air and increases the relative humidity.
What happens to the water vapor in saturated air as the air cools?
Condensation exceeds evaporation and droplets may form.
Distinguish between condensation and precipitation.
During condensation water molecules go from gas to liquid; during precipitation liquid drops grow large enough to fall under gravity.
How do downdrafts form in thunderstorms?
Falling water drops entrain cold air and drag it down toward the surface.
What is the difference between humidity and relative humidity?
Humidity is the amount of water in the air; relative humidity is what percent of the maximum capacity of water is in the air.
Does a rain shadow occur on the windward or the leeward side of a mountain range? Explain.
Leeward, the rising air on the windward side expands, cools, reaches saturation, and produces rain, leaving dry air to descend on the leeward side.
Explain how convectional lifting plays a role in the formation of cumulus clouds.
Warm air rises by convection, expands, and cools, reaching saturation and condensing to form a cloud.
Briefly describe how thunder and lightning develop.
Water drops interact with each other and air to separate electric charges. The electric charges flow together producing lightning. Lightning heats and expands the air creating thunder.
What does saturation point have to do with dew point?
When the ambient temperature equals the dew point the air is saturated.
Under what conditions does orographic precipitation occur?
Wind blows air up a slope where it expands, cools, becomes saturated, and condenses to form rain.
In order for clouds to form,
air must be lifted
Which type of cloud can become a thunderhead?
altocumulus
A front is a contact zone between two different air masses. When two opposing front types (warm/cold) overtake one another and merge, it produces
an occluded front
Which two of the following cloud forms is least likely to produce rain or snow: cirrostratus, nimbostratus, altocumulus, or stratocumulus?
cirrostratus and stratocumulus
On a weather map, areas of high pressure (H on a map) are where air tends to sink. This air tends to produce
clear skies and fair weather
In a rising air mass, when condensation rate exceeds the evaporation rate
cloud droplets begin to form
Air is considered to be unstable if it
continues to rise because it is warmer than the surrounding air
What are the three main atmospheric lifting mechanisms?
convectional, orographic, and frontal
When a parcel of air rises, does it become warmer, cooler, or remain the same temperature?
cooler
As a warm air parcel rises, it
expands due to less atmospheric pressure
Condensation is more likely to occur in cool air because
slower moving water vapor molecules come in contact, leading to increased saturation and relative humidity
As air temperature decreases, does relative humidity increase, decrease, or stay the same?
increase
Compared to cold air, warm air is able to "hold" more water vapor because
it has a higher saturation vapor pressure
he three basic ingredients for thunderstorm formation are
moisture, rising unstable air, and a lifting mechanism that provides a nudge
What happens to the air pressure and temperature of an air parcel as it flows up the side of a mountain?
pressure decreases; temperature decreases
Name ways in which thermal energy in air can be decreased.
radiation to space and evaporation of raindrops, conduction to cold ground, expansion of the air
