Chapter 4

Describe how mountains influence warm air to rise/lapse rate, and temperature+moisture change as air moves up one side and then down the other side of a mountain.

-As air encounters the base of the mountain and begins moving up slope, it is unsaturated. Cools according to unsaturated adiabatic lapse rate -As air flows upslope, at some elevation it has cooled enough that it becomes saturated (reaches dew point) and clouds form. As air continues rising, it now cools at the saturated adiabatic lapse rate.

fog

-cloud at ground level. -produced by cooling of air, by increasing humidity, with water vapor content in the air reaching saturation. -fog indicates that the relative humidity is 100% and air temperature has reached the dew point.

cirriform clouds

-high in the troposphere and have wispy appearance

stratiform clouds

-layered or spread out aspect -form when air is forced upward -composed solely of ice and have wispy sheetlike appearance -mid level clouds: altostratus -nimbostratus: stratiform cloud that is precipitating -stratus: low level stratiform cloud that is not precipitating

precipitation

-process whereby liquid droplets of water (raindrops), solid bits of ice, or a combo fall from the sky. - cycle begins with evaporation of water in the oceans and other parts of Earth's surface, puts water vapor into atmosphere. - water vapor forms various types of clouds -processes occur in clouds that make water droplets or bits of ice heavy that the pull of gravity can overwhelm buoyancy forces that uplift air within the cloud

Cumuliform clouds

-puffy aspect -produced by air rising -air is unstable to a degree -mid level clouds are altocumulus: puffy and wispy -high in atmosphere are cirrocumulus: lumpy and wispy -cumulonimbus clouds: moisture abundant, atmosphere unstable, vertical extent, accompanied by lightning

Dew point

-temperature to which a volume of air must be cooled to become saturated with water vapor. -if air temperature is at the dew point, the air is so saturated with water vapor that vapor condenses as drops of liquid water, like drops in clouds or rain. -figure on 4,4

Vapor pressure

-the pressure exerted by a vapor over a liquid -represented by letter e

Three ways air can reach saturation

1. increasing moisture content until water vapor reaches water vapor capacity 2. cooling the air until it reaches the dew point 3. Combo of cooling and increasing humidity page 126

Which type of pressure do you associate with rising/sinking air

As air rises, pressure decreases As air falls, pressure increases

Rossby waves

Convergence occurs from the way that upper level air circulates around bends in the polar front jet stream

Orographic effect

Mountainous areas represent obstructions to low level winds. As air encounters topography, it slows down, piles up and rises. As air rises, it cools by adiabatic expansion, forming cloud if cools to dew point temp. Thunderstorms common over mountains.

Relative humidity

The percentage of water vapor in the air compared to the maximum amount of water vapor that air can contain at a particular temperature

lapse rate

The rate at which temperature decreases with an increase in altitude....change in temperature for change in height

atmospheric instability

Thunderstorm Ingredients

adiabatic

When there is no energy exchanged between the parcel of land and its surroundings

frontal uplifting

Whenever two air masses with significantly different temperatures meet, the warmer air will be forced up and over the colder air because the warmer air is less dense.

low level convergence

Winds from two systems are moving on a collision course. Easiest way for colliding air is to move upward. pic 122 Also occurs by a wind that is slowed down, such as by friction with the surface. Slowed air causes faster moving air behind it to begin to pile up, forcing some air to rise.

unsaturated adiabatic lapse rate

adiabatic rising air remains unsaturated

Humidity

amount of water vapor in the air

Describe some expressions of atmospheric moisture

clouds, precipitation, storms, weather fronts, and other

Dew

drops of liquid water that condense out of the atmosphere and onto solid surfaces.

List ways water is expressed in the environment

gas (water vapor) liquid solid (ice)

diabatic

means occurring with an exchange of heat

Sketch and describe four settings in which near-surface air can be cooled enough to form fog.

radiation fog: cooling of the ground surface by radiant heat loss. advection fog: When warm air flows over a colder surface, air loses some energy to surface and cools. upslope fog: as air is forced uphill by prevailing local wind, it will cool because of decreasing atmospheric pressure above. At some point air will cool to dew point and cloud will form. valley fog, descending cold air: in mountainous terrain, air near surface cools at night. This air flows downhill because it is more dense than warmer air. Descending air may chill ambient air in the valley and reach dew point to form a fog.

saturated adiabatic lapse rate

rate at which saturated air cools with adiabatic ascent

atmospheric stability

tendency of a parcel of air to remain in place or change its vertical position