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Atmospheric Moisture and Precipitationudel.edu/~ginah/geog152/152_9_moisture_web.pdf · Dry Adiabatic Lapse Rate ... moist adiabatic lapse rate which ranges from between 4°C ...

Apr 09, 2018

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Page 1: Atmospheric Moisture and Precipitationudel.edu/~ginah/geog152/152_9_moisture_web.pdf · Dry Adiabatic Lapse Rate ... moist adiabatic lapse rate which ranges from between 4°C ...

Atmospheric MoistureAtmospheric Moistureand Precipitationand Precipitation

Page 2: Atmospheric Moisture and Precipitationudel.edu/~ginah/geog152/152_9_moisture_web.pdf · Dry Adiabatic Lapse Rate ... moist adiabatic lapse rate which ranges from between 4°C ...

Water is life!Water is life! 71% of the earth is covered in water71% of the earth is covered in water 70% of our body weight is water70% of our body weight is water A human can survive 50-60 days without food; only 2-3 days A human can survive 50-60 days without food; only 2-3 days

without waterwithout water

Page 3: Atmospheric Moisture and Precipitationudel.edu/~ginah/geog152/152_9_moisture_web.pdf · Dry Adiabatic Lapse Rate ... moist adiabatic lapse rate which ranges from between 4°C ...

Characteristics of HCharacteristics of H220:0:

Pure water is odorless, colourless and tastelessPure water is odorless, colourless and tasteless Water is a solvent (pure water rarely exists in nature)Water is a solvent (pure water rarely exists in nature) Water weighs 1g/cm3 or 1kg/LWater weighs 1g/cm3 or 1kg/L Water has three states: solid, liquid and gasWater has three states: solid, liquid and gas

Although there is evidence of water on other planets (Mars) earth is Although there is evidence of water on other planets (Mars) earth is the only planet known to have water in all three phasesthe only planet known to have water in all three phases

Page 4: Atmospheric Moisture and Precipitationudel.edu/~ginah/geog152/152_9_moisture_web.pdf · Dry Adiabatic Lapse Rate ... moist adiabatic lapse rate which ranges from between 4°C ...

The Hydrosphere: the hydrologic reservoirThe Hydrosphere: the hydrologic reservoirHydrosphereHydrosphere – water in the earth-atmosphere system – water in the earth-atmosphere system Earth’s hydrosphere contains 1.36 billion cubic kmEarth’s hydrosphere contains 1.36 billion cubic km

97.22 % (1.321 billion km97.22 % (1.321 billion km33) is located within the oceans ) is located within the oceans (saltwater)(saltwater)

2.78% is freshwater2.78% is freshwater

77.14% of freshwater and 99.357% of surface fresh water is 77.14% of freshwater and 99.357% of surface fresh water is within glaciers and ice sheetswithin glaciers and ice sheets

Less than 1% of freshwater is within lakes, rivers and streamsLess than 1% of freshwater is within lakes, rivers and streams

Page 5: Atmospheric Moisture and Precipitationudel.edu/~ginah/geog152/152_9_moisture_web.pdf · Dry Adiabatic Lapse Rate ... moist adiabatic lapse rate which ranges from between 4°C ...

Water is unique in that it exists in all three states (solid, liquid, gas)Water is unique in that it exists in all three states (solid, liquid, gas) Consists of 2 H atoms and 1 O atom that bond easily Consists of 2 H atoms and 1 O atom that bond easily → hard to separate→ hard to separate Water is a versatile solventWater is a versatile solvent Water is slightly weird as it’s greatest density occurs in the liquid phaseWater is slightly weird as it’s greatest density occurs in the liquid phase Water is able to shift between states very easilyWater is able to shift between states very easily Water exhibits Water exhibits polaritypolarity

WaterWater

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Polarity –Polarity – The 2 H atoms are positively charged and located on one side of The 2 H atoms are positively charged and located on one side of

the moleculethe molecule The 1 O atom is negatively chargedThe 1 O atom is negatively charged This polarity causes water molecules to attract other moleculesThis polarity causes water molecules to attract other molecules

Hydrogen bondingHydrogen bonding

This is why water tends to stick to thingsThis is why water tends to stick to things It also leads to surface tension; allows things with greater density It also leads to surface tension; allows things with greater density

to floatto float Capillarity =Capillarity = water will move into other substances b/c one water water will move into other substances b/c one water

molecule will draw other molecules into itmolecule will draw other molecules into it

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Heat Properties of WaterHeat Properties of Water

For water to change from on phase to another it either For water to change from on phase to another it either absorbs or releases heat energy:absorbs or releases heat energy:

Heat energy is needed to change from phase to another to Heat energy is needed to change from phase to another to break the hydrogen bonds between water moleculesbreak the hydrogen bonds between water molecules

Page 8: Atmospheric Moisture and Precipitationudel.edu/~ginah/geog152/152_9_moisture_web.pdf · Dry Adiabatic Lapse Rate ... moist adiabatic lapse rate which ranges from between 4°C ...

Phase Change –Phase Change – when water changes from one state to when water changes from one state to anotheranother Melting/freezing describe the change between liquid and solidMelting/freezing describe the change between liquid and solid Condensation/evaporation describe the change between liquid and Condensation/evaporation describe the change between liquid and

gasgas Sublimation/deposition describe the direct change between solid Sublimation/deposition describe the direct change between solid

and gasand gas

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Solid Phase:Solid Phase:- Unlike other substances that contract went cooled, water expands Unlike other substances that contract went cooled, water expands

as a solidas a solid- Ice will increase it’s volume up to 9% as it cools to -29 CIce will increase it’s volume up to 9% as it cools to -29 C

- Reason for potholes, and major landforms/weatheringReason for potholes, and major landforms/weathering- Because water expands when it’s a solid (increasing volume) its Because water expands when it’s a solid (increasing volume) its

density decreases (fewer water molecules per unit volume)density decreases (fewer water molecules per unit volume)- Ice has 0.91 times the density of liquid waterIce has 0.91 times the density of liquid water- That’s why ice floatsThat’s why ice floats

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Melting/Freezing:Melting/Freezing:- Melting/freezing occurs at 0 CMelting/freezing occurs at 0 C- For water to move from a solid (ice) to a liquid, heat energy must For water to move from a solid (ice) to a liquid, heat energy must

be supplied to increase the motion of water molecules to break the be supplied to increase the motion of water molecules to break the strong bond achieved as a solidstrong bond achieved as a solid

- There is no change in sensible temperature between ice and water There is no change in sensible temperature between ice and water at 0 Cat 0 C

Latent heatLatent heat of meltingof melting: heat energy absorbed when water goes from : heat energy absorbed when water goes from solid to liquid formsolid to liquid form

Latent heat of fusionLatent heat of fusion: heat energy released when water goes from liquid : heat energy released when water goes from liquid to solid formto solid form

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Liquid phase –Liquid phase – - Water attains its greatest density at 4 CWater attains its greatest density at 4 C- Liquid water has no shape Liquid water has no shape → → water assumes shape of its containerwater assumes shape of its container- Liquid water exists under temperatures between 0 and 100 CLiquid water exists under temperatures between 0 and 100 C

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Evaporation/Condensation phase –Evaporation/Condensation phase – - Evaporation/condensation occurs at 100 CEvaporation/condensation occurs at 100 C- More latent heat energy is absorbed and released when water More latent heat energy is absorbed and released when water

changes phase between liquid and gas than between solid and changes phase between liquid and gas than between solid and liquidliquid

- Greater latent heat energy is needed to increase the motion of Greater latent heat energy is needed to increase the motion of water molecules to break the surface tension created by hydrogen water molecules to break the surface tension created by hydrogen bondingbonding

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Gaseous PhaseGaseous Phase –– water vapor is an invisible gas and each water vapor is an invisible gas and each molecule moves independentlymolecule moves independently

Sublimation/Deposition Sublimation/Deposition – – Water can move directly from a solid to a gas and back without Water can move directly from a solid to a gas and back without

entering the liquid phaseentering the liquid phase

Latent heat of sublimationLatent heat of sublimation – heat absorbed when water moves from a – heat absorbed when water moves from a solid to gaseous state directlysolid to gaseous state directly Happens in your freezerHappens in your freezer When gas moves from a gas to solid phase heat is released; ex frostWhen gas moves from a gas to solid phase heat is released; ex frost

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In Summary:In Summary:

- Energy is absorbed by processes that result in water Energy is absorbed by processes that result in water changing phase from a solid to liquid to gaschanging phase from a solid to liquid to gas

- Energy is released by processes that result in water Energy is released by processes that result in water changing phase from a gas to liquid to solidchanging phase from a gas to liquid to solid

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HumidityHumidity

Page 16: Atmospheric Moisture and Precipitationudel.edu/~ginah/geog152/152_9_moisture_web.pdf · Dry Adiabatic Lapse Rate ... moist adiabatic lapse rate which ranges from between 4°C ...

Humidity:Humidity: the water vapor content of the air the water vapor content of the air

The capacity of air to hold water is primarily a function of air The capacity of air to hold water is primarily a function of air temperaturetemperature

Warmer air has a greater capacity to hold water vapor than Warmer air has a greater capacity to hold water vapor than cooler aircooler air

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Relative Humidity:Relative Humidity:

After air temperature and air pressure, relative humidity is the most After air temperature and air pressure, relative humidity is the most common piece of information in local weather broadcastscommon piece of information in local weather broadcasts

Relative HumidityRelative Humidity - - the ratio (expressed as a percentage) of the actual the ratio (expressed as a percentage) of the actual amount of water vapor in the air (content) to the amount of water vapor amount of water vapor in the air (content) to the amount of water vapor the air can hold at that temperature (capacity)the air can hold at that temperature (capacity)

RH = (water vapor RH = (water vapor contentcontent / maximum water vapor / maximum water vapor capacitycapacity) * 100) * 100

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Relative Humidity:Relative Humidity: Varies b/c of evaporation/condensation, or temperature changesVaries b/c of evaporation/condensation, or temperature changes Condensation and evaporation happen continuouslyCondensation and evaporation happen continuously Consider warm air to be a large sponge that soaks up large Consider warm air to be a large sponge that soaks up large

quantities of water vaporquantities of water vapor Think of cooler air as a small sponge that can only soak up small Think of cooler air as a small sponge that can only soak up small

quantities of water vaporquantities of water vapor

The amount of water it takes to fill up cooler air may only partially fill The amount of water it takes to fill up cooler air may only partially fill up warmer airup warmer air

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Saturation -Saturation - occurs when a particle of air contains all the occurs when a particle of air contains all the water vapor it can hold (it is filled to capacity)water vapor it can hold (it is filled to capacity)

RH is at 100% (the ratio of water vapor content equal the air’s RH is at 100% (the ratio of water vapor content equal the air’s capacity to hold water vapor)capacity to hold water vapor)

The net transfer of water molecules between the surface and the The net transfer of water molecules between the surface and the air reaches equlibrium (rates of condensation and evaporation are air reaches equlibrium (rates of condensation and evaporation are equal)equal)

To go past saturation will result in condensationTo go past saturation will result in condensation You can pass saturation by decreasing air temperature (decrease the You can pass saturation by decreasing air temperature (decrease the

air’s capacity to hold water vapor)air’s capacity to hold water vapor) It may not rain when RH = 100% but if the air goes past it , precipitation It may not rain when RH = 100% but if the air goes past it , precipitation

will occurwill occur

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Dew Point Temperature -Dew Point Temperature - the temperature at which a given mass of the temperature at which a given mass of air will become saturated given the amount of water vapor contained air will become saturated given the amount of water vapor contained within that air parcelwithin that air parcel

Air is saturated when the dew point temperature and the air Air is saturated when the dew point temperature and the air temperature are equaltemperature are equal

At this point RH = 100%At this point RH = 100%

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Relative Humidity PatternsRelative Humidity Patterns

b/c the capacity of air to hold water vapor increases as air temperature b/c the capacity of air to hold water vapor increases as air temperature increases, the daily values of air temperature and relative humidity are increases, the daily values of air temperature and relative humidity are inversely relatedinversely related - air temperature rise from just after sunrise to mid-afternoonair temperature rise from just after sunrise to mid-afternoon- Given a constant water vapor content as air temperature rises, Given a constant water vapor content as air temperature rises,

relative humidity will relative humidity will decreasedecrease

Daily RH: Daily RH: - Relative humidity is highest at dawn when air temperature is lowestRelative humidity is highest at dawn when air temperature is lowest- Relative humidity is lowest around mid-afternoon when temperature Relative humidity is lowest around mid-afternoon when temperature

and the capacity to hold water vapor is highestand the capacity to hold water vapor is highest

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Vapor Pressure –Vapor Pressure – the portion of the air pressure exerted by water the portion of the air pressure exerted by water molecules within the atmospheremolecules within the atmosphere

Saturation Vapor Pressure –Saturation Vapor Pressure – the maximum pressure that water the maximum pressure that water vapor molecules can exertvapor molecules can exert Occurs when air has reached the max capacity to hold water vapor at the Occurs when air has reached the max capacity to hold water vapor at the

given temperaturegiven temperature Saturation vapor pressure increases exponentially with increasing Saturation vapor pressure increases exponentially with increasing

temperature temperature → higher temp can hold more water vapor→ higher temp can hold more water vapor Saturation vapor pressure is higher over water than iceSaturation vapor pressure is higher over water than ice

Page 23: Atmospheric Moisture and Precipitationudel.edu/~ginah/geog152/152_9_moisture_web.pdf · Dry Adiabatic Lapse Rate ... moist adiabatic lapse rate which ranges from between 4°C ...

Specific Humidity –Specific Humidity – measure of the actual amount of water vapor in measure of the actual amount of water vapor in the airthe air

S.H. = mass of water vapor (g) / mass of air (kg)S.H. = mass of water vapor (g) / mass of air (kg)

it takes into account the actual mass of water vapor in the airit takes into account the actual mass of water vapor in the air It is not affected by changes in temperatureIt is not affected by changes in temperature Maximum specific humidity –Maximum specific humidity – is the maximum mass of water is the maximum mass of water

vapor that a kg of air can hold at any specified temperaturevapor that a kg of air can hold at any specified temperature

Page 24: Atmospheric Moisture and Precipitationudel.edu/~ginah/geog152/152_9_moisture_web.pdf · Dry Adiabatic Lapse Rate ... moist adiabatic lapse rate which ranges from between 4°C ...

Measuring Humidity:Measuring Humidity:

Hair hygrometer –Hair hygrometer – measures humidity based on the change in length measures humidity based on the change in length of a piece of human hairof a piece of human hair Human hair changes by as much as 4% in length between 0 and Human hair changes by as much as 4% in length between 0 and

100% relative humidity100% relative humidity

Sling Psychrometer –Sling Psychrometer – measures the rate at which water evaporates measures the rate at which water evaporates from a wet wickfrom a wet wick One thermometer measures air temp (dry bulb)One thermometer measures air temp (dry bulb) The bottom of one thermometer is wrapped in a wet clothThe bottom of one thermometer is wrapped in a wet cloth

That thermometer measures the temperature relative to the rate of That thermometer measures the temperature relative to the rate of evaporation from the wickevaporation from the wick

Evaporation cools the wickEvaporation cools the wick

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Atmospheric StabilityAtmospheric Stability

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When talking about atmospheric stability, we will use the When talking about atmospheric stability, we will use the term term parcel parcel of airof air

Parcel Parcel – term used to describe a body of air with specific – term used to describe a body of air with specific temperature and humidity characteristics.temperature and humidity characteristics.

Page 27: Atmospheric Moisture and Precipitationudel.edu/~ginah/geog152/152_9_moisture_web.pdf · Dry Adiabatic Lapse Rate ... moist adiabatic lapse rate which ranges from between 4°C ...

Two forces determine the motion of an air parcel:Two forces determine the motion of an air parcel:

Bouyant force:Bouyant force: moves an air parcel up moves an air parcel up An air parcel of lower density will riseAn air parcel of lower density will rise As it rises it will expand as external pressure decreasesAs it rises it will expand as external pressure decreases

Gravitational force:Gravitational force: moves an air parcel down moves an air parcel down A parcel of higher density will fallA parcel of higher density will fall As it falls it compresses as external pressure increasesAs it falls it compresses as external pressure increases

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Stability –Stability – the tendency of a parcel to remain in place or to the tendency of a parcel to remain in place or to change vertical position by rising or fallingchange vertical position by rising or falling

A parcel is A parcel is stablestable if it resists vertical motion if it resists vertical motion A parcel is A parcel is unstableunstable if it continues to rise until it reaches an if it continues to rise until it reaches an

elevation where the surrounding atmosphere has a density or air elevation where the surrounding atmosphere has a density or air temperature similar to that of the parceltemperature similar to that of the parcel

Changes in a parcel’s vertical position will affect the amount of Changes in a parcel’s vertical position will affect the amount of moisture it can containmoisture it can contain

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Adiabatic Processes:Adiabatic Processes:

Determining Determining atmospheric stabilityatmospheric stability requires the temperature of requires the temperature of the parcel and surrounding air:the parcel and surrounding air:

Ex:Ex: a parcel that is warmer than the surrounding air will rise until it is a parcel that is warmer than the surrounding air will rise until it is cooled to the same temperature as the surrounding air, at which point cooled to the same temperature as the surrounding air, at which point it will cease to riseit will cease to rise

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Normal lapse rate –Normal lapse rate – average decrease in air temperature with average decrease in air temperature with elevation (6.4 C/km)elevation (6.4 C/km)

Environmental Lapse Rate –Environmental Lapse Rate – actual decrease in air actual decrease in air temperature with elevationtemperature with elevation

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A A rising parcelrising parcel will cool by expansion resulting from a decrease in will cool by expansion resulting from a decrease in pressure with increasing elevationpressure with increasing elevation As pressure decreases, a parcel will expand and it’s internal temperature As pressure decreases, a parcel will expand and it’s internal temperature

and density will decreaseand density will decrease Temperature decreases b/c sensible heat is consumed in the process of Temperature decreases b/c sensible heat is consumed in the process of

expansionexpansion

A A falling parcelfalling parcel will warm by compression resulting from an increase in will warm by compression resulting from an increase in pressure with decreasing elevationpressure with decreasing elevation As pressure increases, a parcel will compress and its internal temperature As pressure increases, a parcel will compress and its internal temperature

and density will increaseand density will increase Temperature increases b/c sensible heat is produced in the process of Temperature increases b/c sensible heat is produced in the process of

compressioncompression

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These temperature changes within individual parcels of air occur These temperature changes within individual parcels of air occur without any significant heat exchange between surrounding without any significant heat exchange between surrounding environment and the parcelenvironment and the parcel

Temperature changes within a parcel that occur b/c of expansion and Temperature changes within a parcel that occur b/c of expansion and compression are compression are AdiabaticAdiabatic

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Adiabatic processes –Adiabatic processes – describe the cooling and warming rates of describe the cooling and warming rates of individual parcels of air due to expansion and compression of the individual parcels of air due to expansion and compression of the parcel rather than energy exchange between the parcel and parcel rather than energy exchange between the parcel and surrounding airsurrounding air

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There are two adiabatic rates for a vertically moving parcel, depending on There are two adiabatic rates for a vertically moving parcel, depending on moisture conditions of the parcel:moisture conditions of the parcel:

Dry Adiabatic Lapse Rate (DAR or Dry Adiabatic Lapse Rate (DAR or ΓΓdd)) – the rate at which rising dry air cools – the rate at which rising dry air cools by expansion or falling dry warms by compressionby expansion or falling dry warms by compression Used for air that is not saturated (has a RH < 100%)Used for air that is not saturated (has a RH < 100%) Has an average value of 10 C/kmHas an average value of 10 C/km

Moist Adiabatic Lapse Rate (WAR/ Moist Adiabatic Lapse Rate (WAR/ ΓΓmm) ) –– rate at which rising moist air cools by rate at which rising moist air cools by expansion or falling moist air warms by compressionexpansion or falling moist air warms by compression used for saturated air (RH = 100%)used for saturated air (RH = 100%) Has an average value of 6 C/kmHas an average value of 6 C/km This is lower that the DAR b/c of the latent heat of condensationThis is lower that the DAR b/c of the latent heat of condensation

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Rising air will cool and it is possible that it will reach the dew Rising air will cool and it is possible that it will reach the dew point temperature (a relative humidity of 100%)point temperature (a relative humidity of 100%)

At that point, or the At that point, or the lifting condensation levellifting condensation level, moisture will , moisture will condense from the air and the air temperature will follow the condense from the air and the air temperature will follow the moist adiabatic lapse ratemoist adiabatic lapse rate which ranges from between 4°C which ranges from between 4°C and 9°C per kilometer (avg 6 C/km)and 9°C per kilometer (avg 6 C/km)

The wet adiabatic lapse rate will be lower for warmer air since The wet adiabatic lapse rate will be lower for warmer air since there is more moisture to condensethere is more moisture to condense

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Stable vs. Unstable Atmospheric Stable vs. Unstable Atmospheric ConditionsConditions

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Temperature relationships with rising and falling air parcels Temperature relationships with rising and falling air parcels causes three atmospheric conditions:causes three atmospheric conditions:

2.2. Unstable Unstable 3.3. Conditionally stableConditionally stable4.4. StableStable

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Unstable –Unstable – atmospheric conditions that occur when an air parcel is atmospheric conditions that occur when an air parcel is warmer than the surrounding air and continues to risewarmer than the surrounding air and continues to rise

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Unstable:Unstable: the environmental lapse rate is greater than the DAR and MARthe environmental lapse rate is greater than the DAR and MAR The parcel cools at the DAR making it warmer than the surrounding airThe parcel cools at the DAR making it warmer than the surrounding air As long as the parcel is warmer it continues to riseAs long as the parcel is warmer it continues to rise Eventually the parcel will cool until it’s temperature is equal to the dew Eventually the parcel will cool until it’s temperature is equal to the dew

point temperature point temperature → RH = 100%→ RH = 100% Water vapor in parcel will condense, forming clouds and possible Water vapor in parcel will condense, forming clouds and possible

precipitationprecipitation

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Conditionally Unstable –Conditionally Unstable – atmospheric conditions that occur when a atmospheric conditions that occur when a parcel rising according to the DAR will resist upward movement but a parcel rising according to the DAR will resist upward movement but a parcel rising according to the MAR will continue to riseparcel rising according to the MAR will continue to rise

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Conditionally Stable:Conditionally Stable: The environmental lapse rate is greater than the MAR but lower than The environmental lapse rate is greater than the MAR but lower than

the DARthe DAR Unsaturated air will rise according to the DARUnsaturated air will rise according to the DAR Saturated air will rise according to the MARSaturated air will rise according to the MAR

The surrounding air cools at a rate of 7 C/km and the parcel cools at 6 The surrounding air cools at a rate of 7 C/km and the parcel cools at 6 C/kmC/km

At 1000m the parcel will still be warmer than the surrounding airAt 1000m the parcel will still be warmer than the surrounding air As long as it’s warmer it will continue to rise under unstable conditionsAs long as it’s warmer it will continue to rise under unstable conditions

Stability is dependent on the moisture content of the air parcelStability is dependent on the moisture content of the air parcel

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Stable –Stable – atmospheric conditions that occur when a parcel rising atmospheric conditions that occur when a parcel rising according to the DAR and MAR will resist upward motionaccording to the DAR and MAR will resist upward motion

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Stable:Stable: The environmental lapse rate is lower than the MAR and the DARThe environmental lapse rate is lower than the MAR and the DAR Parcel will not rise and clouds will not formParcel will not rise and clouds will not form

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CloudsClouds

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Cloud –Cloud – an aggregation of tiny moisture droplets and ice an aggregation of tiny moisture droplets and ice crystals that are suspended in air, with great enough crystals that are suspended in air, with great enough volume to be visiblevolume to be visible

Form when air becomes saturated with waterForm when air becomes saturated with water Fog – a cloud in contact with the groundFog – a cloud in contact with the ground

Clouds and Cloud FormationClouds and Cloud Formation

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Clouds form when water vapor within a saturated air parcel condenseClouds form when water vapor within a saturated air parcel condense A parcel will rise until its internal temperature is cooled to the dew point A parcel will rise until its internal temperature is cooled to the dew point

temperaturetemperature As the condensation occurs it warms the parcel and the parcel continues to As the condensation occurs it warms the parcel and the parcel continues to

rise and coolrise and cool Condensation continues as the parcel risesCondensation continues as the parcel rises Liquid water will condense around cloud condensation nucleiLiquid water will condense around cloud condensation nuclei If there is enough condensation and the moisture droplets are large If there is enough condensation and the moisture droplets are large

enough, eventually the force of gravity will pull them toward the surfece enough, eventually the force of gravity will pull them toward the surfece (precipitation)(precipitation)

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Cloud Types:Cloud Types:

Clouds are classified by altitude and shape:Clouds are classified by altitude and shape:

Strat Strat → horizontal→ horizontal CumuloCumulo → puffy → puffy

Nimbus Nimbus → precipitation→ precipitation

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Frozen water moleculesWispyHigh altitudeCirrus

thunderstormsVertical

Cumulonimbus

Contain water and iceMany stylesMiddle altitudeAltocumulus

GreyLumpyLow altitudeStratocumulus

PrecipitationHorizontalLow altitudeNimbostratus

GlobularLow altitudeCumulus

HorizontalLow altitudeStratus

CharacteristicsShape:Altitude:Name:

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CirrostratusCirrostratus

When viewed through a When viewed through a layer of cirrostratus, the layer of cirrostratus, the Moon or Sun has a Moon or Sun has a whitish, milky appearance whitish, milky appearance but a clear outline. A but a clear outline. A characteristic feature of characteristic feature of cirrostratus clouds is the cirrostratus clouds is the halohalo, a circular arc around , a circular arc around the Sun or Moon formed by the Sun or Moon formed by the refraction (bending) of the refraction (bending) of light as it passes through light as it passes through the ice crystals.the ice crystals.

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altocumulus standingaltocumulus standinglenticularuslenticularus

Lenticular CloudsLenticular Clouds

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Stratiform CloudsStratiform Clouds

FogFog – stratus cloud at the ground– stratus cloud at the ground

Advection FogAdvection Fog – moving air over a colder surface – moving air over a colder surface (e.g., the Grand Banks of Newfoundland)(e.g., the Grand Banks of Newfoundland)

Radiation FogRadiation Fog – motionless air that cools below the dew point – motionless air that cools below the dew point due to longwave radiation loss at nightdue to longwave radiation loss at night

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Radiation Fog in the Central Valley of CaliforniaRadiation Fog in the Central Valley of California

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Stratiform CloudsStratiform Clouds

FogFog – stratus cloud at the ground– stratus cloud at the ground

Sea FogSea Fog – forms when a cool moist air parcel comes in contact – forms when a cool moist air parcel comes in contact with cold oceanwith cold ocean

Occurs along the coasts of continents where cold currents move Occurs along the coasts of continents where cold currents move toward the equator (e.g. California, Peru)toward the equator (e.g. California, Peru)

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