The Natural Environment Exam 2

Cloud-Albedo Forcing

Increase in albedo caused by stratus clouds due to their reflection of insolation

Cold Front

The leaning edge of an advancing cold air mass

Condensation Nucleus

A tiny particle in the atmosphere that serves as a surface for water vapor to condense upon, forming cloud droplets

Convection

Movement of molecules and transfer of energy within gases and liquids

Coriolis Effect

Effect of Earth’s rotation tending to turn the direction of motion of any object

• Northern Hemisphere —→ Right

• Southern Hemisphere ——> Left

Cyclone

Center of atmospheric pressure where air converges and rises inward, forming an spiral

• Northern Hemisphere —→ Counterclockwise

• Souther Hemisphere ——> Clockwise

Dew Point Temperature

Temperature at which a parcel of air becomes saturated and condensation begins

Hadley Cells

Occurs on either side of the equator and transports warm air toward the subtropics

Isobars

Lines on a weather map connecting points of equal pressure; densely spaced lines indicate fast blowing wind

Pressure-Gradient Force

Force acting horizontally that moves air between high to low pressure (unequal heating of Earth’s surface)

(Shaking a pop can, the pressure building up, opening it, liquid releases outside to the lower atmospheric pressure)

Rain Shadow

The area on the leeward slope of a mountain range where precipitation receipt is greatly reduced compared to the windward slope on the other side

Relative Humidity

Ratio (fraction) of water vapor present in air to maximum amount it could hold; varies because of changes in amount of water vapor in air or air temperature; air is saturated when relative humidity is 100%

(warm air has a greater capacity for water vapor than cold air)

Land/Sea Breeze

Clear Day

• Sun heats land surface rapidly

• Warm air is less dense

• Low pressure forms over land as warm air rises

• Clear Night'

• -Cooler air

• -More Dense

• -High pressure (Air sinks)

Trade Winds

Surface winds in low latitudes that converge on the equatorial low-pressure trough from subtropical high-pressure belts

• Strong and dependable

• Pick up large amounts of moisture

• Northeast trades in Nothern hemisphere, South in Southern

Urban Heat Island

Developed area that is significantly warmer than surrounding rural area

Wet Adiabatic Lapse Rate

Rate at which a rising parcel of air that IS saturated cools by expansion; WAR<DAR because latent heat is released when condensation occurs after dew-point temperature is reached

Cloud Greenhouse Forcing

Increase in greenhouse warming caused by cirrus clouds

Conduction

Transmission of heat energy through matter by transfer of energy from one atom or molecule to the next in the direction of decreasing temperature

Convection

Movement of molecules and transfer of energy within gases and liquids

Radiation

The transfer of energy via electromagnetic waves. It can travel through a vacuum (heat from sun reaching Earth)

Temperature

A measure of sensible heat energy present in the atmosphere and other media; indicates the average kinetic energy of individual molecules within a substance

Heat

The flow of kinetic energy from one body to another because of a temperature difference between them

Urban Heat Island

An urban microclimate that is warmer on average than areas in the surrounding countryside because of the interaction of solar radiation and various surface characteristics

(Replacement of natural landscapes with surfaces such as pavement and buildings that absorb heat. With the lack of vegetation and water, the buildings trap heat.)

Evaporation

Process of turning liquid into vapor

Transparency

The transparency of water results in the distribution of available heat energy over a greater volume and depth of which occurs on land

Specific Heat

The heat capacity of a substance

The specific heat of water is about 4 times that of soil

Movement

The movement of currents results in a mixing of cooler and warmer waters, which spreads the available energy over a greater volume than if the water were still

Atmospheric Pressure

Pressure exerted by the atmosphere because of the force of gravity acting on the overwhelming column of air 

Wind

Air motion relative to Earth’s surface; predominantly horizantal

How Wind is Measured

Wind direction is measured as the direction from which it is coming, not toward which it is blowing

Gravitational Force

Force that equally compresses atmosphere around the world

• Density of atmosphere decreases as altitude increases

Friction Force

Decreases wind speed (drag) as it moves across Earth’s surface

• Force varies with surface texture, wind speed, time of day and year, and atmospheric conditions

• Generally, rougher surfaces produce more friction

Anticyclone

Center of high atmospheric pressure where air descends from above and moves outward, forming an outspiral

• Northern Hemisphere (Outspiral, clockwise)

• Southern Hemisphere (Inspiral, counterclockwise)

Latent Heat

Amount of energy released or absorbed by a substance during a change of state or phase

Humidty

Amount of water vapor in the air

(More vapor makes air feel warmer than actual temp)

Specific Humidity

Actual quantity or mass of water vapor in a parcel of air

(Change of temperature has no effect, it’s a measure of mass)

Saturation

Air holds maximum amount of water vapor possible; if air cools further, condensation occurs and clouds will form

Lifting Condensation Level (LCL)

Elevation at which a parcel of air becomes saturated and condensation begins, typically corresponds with bottom level of clouds

Dry Adiabatic Lapse Rate

Rate at which rising air is cooled by expansion, or descending air heats by compression when NO condensation is occurring

Clouds

Dense concentration of suspended water or ice particles in the air

(Particles are super tiny)

Precipitation

Forms by collision and coalescence (merge into one) or formation of ice crystals

(Sleet and ice storms, hail)

Air Masses Rise By…

• Convergent Lifting

• Convectional Lifting

• Orographic Lifting

• Frontal Lifting

Convergent Lifting

Vertical uplift due to increased HORIZONTAL air movement into a single area

(Convergence of trade winds on either side of the ITCZ equator)

Convectional Lifting

Vertical uplift due to CONVECTIVE heating, driven by surface heating that leads to VERTICAL instability

(Urban Heat Island)

Instability at the Equator is Caused By…

Com bination of Convergent and Convectional lifting

Orographic Lifting

Vertical lift due to topographic obstruction, such as a mountain

Windward Slope

Upwind side or side directly influenced by the direction that wind blows

Leeward Slope

Downward side; drier far-side slope

Rain Shadows

Belt of dry climate produced by adiabatic warming of descending air

Frontal Lifting

Boundary between two unlike air masses

Warm Front

Leading edge of warm air mass

Cold Front Characteristics + Formation

• Dense, cold air mass near the surface

• Cold fronts form when a mass of cold air moves into an area with warmer air, causing the warm air to rise up and over the cold air.

Warm Front Characteristics + Formation

• Lighter air

• Warm fronts form when a warm air mass moves into and overtakes a cooler, denser mass

Cold Front Speed + Cloud Type

• Heavy and dense precipitation\

• Short rain duration

• Cumulonimbus Clouds

• Fast speed

Warm Front Speed + Cloud Type

• Light and steady rain

• Long rain duration

• Stratus clouds

• Slow speed

Squall Line

• An advancing wall of cumulonimbus clouds

• May signal that a storm is coming

Four Hemispheric Pressure Areas

• Equatorial Low-Pressure Trough (10N,10S)

• Polar High-Pressure Cells (90N,90S)

• Subtropical High-Pressure Cells (25 to 35 N & S)

• Subpolar Low-Pressure Cells (60N,60S)

Equatorial Low-Pressure Trough (Doldrums)

Atmospheric low-pressure belt over the equator

ITCZ

Narrow zone within equatorial low-pressure trough where trade winds converge; migrates Northward and Southward by season

Subpolar Low-Pressure Cells

Region of low pressure centered approximately 60 degrees, weakens in summer and strengthens in winter

Prevailing Westerlies

Surface winds blowing from a generally westerly direction in the midlatitudes (our neck of the woods), but varying greatly in direction and intensity

Polar High-Pressure Cells

Weak high-pressure cells that form over polar regions, where air is intensely cold