physical geography chapter 6 – Flashcards
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properties of water
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liquidity, ice expansion, surface tension, capillarity, solvent ability, specific heat
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hydrologic cycle
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a series of storage areas interconnected by various transfer processes in which there is a ceaseless interchange of moisture in terms of its geographical location and its physical state
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latent heat
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energy stored or released when a substance changes state
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phase changes of water
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melting, freezing, evaporation, condensation, sublimation, deposition
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sublimation
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water vapor converted directly to ice (energy released) or vice versa (energy stored)
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evaporation
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liquid water is converted to gaseous water vapor (energy absorbed)
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condensation
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water vapor is converted to liquid water (energy released)
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melting
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ice changes to water (energy absorbed)
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freezing
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liquid water changes to solid state ice (energy released)
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rate of evaporation
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depends on temperature, water vapor content of air, wind
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temperature (rate of evaporation)
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water molecules in warm water are more agitated, therefore more evaporation in warm than cold
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transpiration
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plants give up moisture through their leaves
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evapotranspiration
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the transfer of moisture to the atmosphere by transpiration from plants and evaporation from soil and plants
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potential evapotranspiration
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amount of evapotranspiration that would occur if the ground at the location were sopping wet all the time
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humidity
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amount of water vapor in the air
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3 measures of humidity
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absolute, specific, vapor pressure
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absolute humidity
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mass of water vapor in a given volume of air (g/m^3)
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specific humidity
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mass of water vapor in a given mass of air (g/kg)
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vapor pressure
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contribution of water vapor to total pressure of atmosphere
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saturation
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occurs when no more of something can be absorbed, combined with, or added. capacity may be called "saturation absolute humidity" etc. (pg 149)
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relative humidity
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describes how close air is to saturation with water vapor
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relative humidity formula
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actual water vapor in air/capacity (saturation) X100
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relative humidity and temperature
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temperature increases, RH decreases temperature decreases, RH increases
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psychrometer
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instrument used to measure humidity
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dew point temperature
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the critical air temperature at which water vapor saturation is reached
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adiabatic lapse rate vs. environmental lapse rate
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adiabatic deals with air rising or descending, environmental deals with temperature of STILL air
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saturated adiabatic lapse rate vs unsaturated
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unsaturated- RH less than 100%, 10*C/1000m (dry) saturated- 6*C/1000m (moist)
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lifting condensation level
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the altitude at which rising air cools sufficiently to reach 100% RH at the dew point temperature, and condensation begins
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clouds
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visible accumulation of tiny liquid water droplets or ice crystals suspended in the atmosphere
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3 cloud forms
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cirriform, stratiform, cumuliform
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cirriform clouds
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thin wispy and composed of ice crystals rather than water droplets
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stratiform clouds
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appear as grayish sheets that cover most or all of the sky, rarely broken up into individual cloud units
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cumuliform clouds
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massive and rounded, usually with flat base and limited horizontal extent but often billowing upward to great heights
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4 cloud families
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high clouds, middle clouds, low clouds, clouds of vertical development
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high clouds
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above 6 km, thin, white, composed of ice crystals, approaching weather system or storm -cirrus, cirrocumulus, and cirrostratus
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middle clouds
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b/w 2-6 km, may be stratiform or cumuliform composed of liquid water -altocumulus (indicates settled weather) or altostratus (indicates changing weather)
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low clouds
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below 2 km, appear as overcast, widespread, drizzly rain -stratus, stratocumulus, and nimbostratus
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clouds of vertical development
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grows upward from low bases, horizontal spread restricted, indicate active vertical movements in air -cumulus (indicates fair weather) and cumulonimbus (storm clouds)
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cirrus cloud
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high cirriform clouds of feathery appearance
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stratus cloud
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layered horizontal clouds, overcast, below 2 km (low clouds)
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cumulus cloud
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puffy white cloud that forms from rising columns of air
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nimbostratus cloud
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precipitation, develops from stratiform
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cumulonimbus cloud
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tall cumulus cloud associated with rain, thunderstorms, other severe weather like tornadoes and hurricanes
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fog
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a cloud on the ground
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cloud formation
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from adiabatic cooling in rising air
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fog formation
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no uplift like clouds, form by earths surface cools below dew point temp or when enough water vapor is added to air to saturate it
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4 types of fogs
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radiation, advection, upslope, and evaporation fogs
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radiation fog
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when ground loses heat through radiation @ night, heat goes to higher areas, cool ground, fog condenses at dew point in low areas
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advection fog
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when warm moist air moves horizontally over cold surface (air moving from sea to land)
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upslope fog
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created by adiabatic cooling when humid air climbs a topographic slope (Mountain)
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evaporation fog
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when water vapor is added to cold air that is already near saturation
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dew
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the condensation of beads of water on relatively cold surfaces
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frost
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temperature is below freezing, ice crystals rather than water droplets are formed
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buoyancy
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tendency of an object to rise or sink in a fluid under the influence of gravity
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atmospheric stability
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non buoyant, air resists uplift, cold air below warm air
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stable vs unstable air mass
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unstable air rises without external force other than buoyant force, if mass of air is warmer than surrounding air = unstable, clouds form in unstable
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collision, ice-crystal formation
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2 processes that form precipitation
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collision/coalescence
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tiny droplets in tropic clouds merge (coalesce) into larger drops
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Hydrogen bond
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Attraction between a slightly positive hydrogen atom and a slightly negative atom.
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Surface Tension
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a thin skin of molecules forms on the surface of liquid water, causing it to bend.
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Capillarity
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property of water where adhesion and cohesion enable water molecules to move upward through narrow tubes against the force of gravity
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Latent heat of condensation
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When water vapor molecules release energy
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Latent heat of evaporatoin
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the heat lost to the air during evaporation
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Saturation vapor pressure
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the maximum pressure that water vapor molecules could exert if the air were saturated. Varies directly with temperature.
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Capacity
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The maximum amount of water vapor that can me in the air at a given temperature
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dew point
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The temperature at which condensation begins
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Sensible temperature
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Sensation of temperature That the human body feels in contrast to actual temperature
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Supersatuated
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When a solution has more solute than it can hold.
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Condensation Nucli
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soild particles in which clouds form around
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Supercooled water
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water droplets having tempatures below freezing that remain in liquid state
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Dry adiabatic rate
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10c/1000m
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Precipitation
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Any form of water that falls from clouds and reaches Earth's surface.
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What is the international classification scheme for clouds?
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What are the characteristics of stable and unstable air?
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Rain
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drops or liquid water
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snow
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solid precipitation in the form of ice crystals, small pallets, or flakes
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Hail
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small pellets or larger lumps of ice
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Convective lifting
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when a rising parcel of air is warmer than its surroundings
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What are the 4 basic type of atmospheric lifting and precipitation
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Orographic lifting
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cloud formation that occurs when warm moist air is forced to rise up the side of a mountain
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Rain shadow
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A drier area on the leeward side of a mountain range
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Frontal lifting
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if warm and cool air collide, the warm air will be forced up
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convergent lifting
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air flowing from different directions into the same low-pressure area is converging, or displacing, air.
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isohyet
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lines of equal rainfall
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precipitation variability
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Expected departure from average precipitation during any given year
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acid rain
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Rain containing acids that form in the atmosphere when industrial gas emissions (especially sulfur dioxide and nitrogen oxides) combine with water.
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What is a hydrogen bond?
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The attraction between the negative (oxygen) side of one water molecule, to the positive (hydrogen) side of another.
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What happens to the volume of water when it freezes?
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As liquid water freezes into ice, its volume increases
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How does the specific heat of water influence haw rapidly it warms during the summer?
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About 5 times as much energy is needed to increase the temperature of water as a comparable mass of soil or rock, slowing water's rate of warming in summer.
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Why doesn't the temperature of a block of ice increase while it is melting?
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In order for ice to melt, it must absorb energy (the latent heat of melting) to break bonds and allow a phase change. This energy does not increase the temperature of water.
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What happens to the rate of evaporation as air approaches saturation?
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As air comes close to saturation with water vapor, the rate of evaporation drops off sharply
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What does it mean when the absolute humidity of the air is 10 g/m^3
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10 grams of water as vapor are in each cubic meter of air.
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if the water vapor content of air is 5 g/kg and the capacity is 20 g/kg, what is the relative humidity?
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5 g / 20 g = 1/4 or 25 % RH
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What happens to the relative humidity of unsaturated air if the temperature decreases? Why?
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As temperature decreases, water vapor capacity decreases, so RH increases
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Name the two conditions necessary for condensation to occur?
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Condensation can take place when the air reaches 100% RH if surfaces, such as condensation Nucli, are available.
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Why does air rising above the lifting condensation level cool at a lesser rate than air rising below the lifting condensation level?
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Above the lifting condensation level, rising air is expanding and cooling adiabatically, but latent heat released condensation counteracts some of this cooling.
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Name the 3 main forms by which clouds are classified?
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The 3 cloud forms are Cirriform, stratiform, and cumuliform.
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What makes a parcel of air unstable?
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if it is warmer and less dense than the air surrounding it.
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Why is hail associated with highly unstable air?
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it is associated with strong updrafts in cumulonimbus clouds.
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What causes a rain shadow?
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When air is forced to rise on the windward side of a mountain, adiabatically cooling often leads to precipitation and cloud formation; air on the leeward side of the mountain (in the rain shadow) has lost moisture rising up the windward side, it will warm adiabatically, reducing its RH even more.
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Why do equatorial regions generally have high annual precipitation?
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warm, moist air rising in the ITCZ leads to high rainfall.
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Why do west coast locations at about 25 N to 30 N and S typically have low annual precipitation?
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the decending air of the subtropical highs leads to dry conditions
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Is a dessert likely to have high precipitation variability or low?
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deserts will have high precipitation variability from year to year.
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What are the main sources of acid rain?
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Sulfur dioxide (SO2) from powerplants and nitrogen oxides (NO) from vehicle exhaust are common sources of the chemicals that lead to acid rain.
