WATER IN THE WATER IN THE ATMOSPHEREATMOSPHERE

CHAPTER 18.1 HUMIDITY AND CHAPTER 18.1 HUMIDITY AND CONDENSATIONCONDENSATION

CHARACTERISTICS OF WATERCHARACTERISTICS OF WATERDO NOT WRITEDO NOT WRITE

WATER IS UNIQUE BECAUSE IT WATER IS UNIQUE BECAUSE IT EXISTS IN ALL THREE PHASES OF EXISTS IN ALL THREE PHASES OF MATER IN NATUREMATER IN NATURE

SOLID – 0SOLID – 000C OR BELOWC OR BELOW LIQUID – 0LIQUID – 000C – 100C – 10000CC GAS – 100GAS – 10000C OR ABOVE – C OR ABOVE – WATER WATER

VAPORVAPOR AN INVISIBLE GAS AN INVISIBLE GAS

EVAPORATIONEVAPORATION

CHANGE FROM LIQUID TO GASCHANGE FROM LIQUID TO GAS ABSORBS HEATABSORBS HEAT COOLING PROCESSCOOLING PROCESS

EX. SWIMMING POOL OR SWEATINGEX. SWIMMING POOL OR SWEATING

HH22O MOLECULES ABSORB HEAT O MOLECULES ABSORB HEAT FROM YOUR BODYFROM YOUR BODY

CONDENSATIONCONDENSATION

CHANGE FROM GAS TO LIQUIDCHANGE FROM GAS TO LIQUID RELEASES HEATRELEASES HEAT

EX. GLASS OF WATER IN FREEZEREX. GLASS OF WATER IN FREEZER

TYPES OF CONDENSATIONTYPES OF CONDENSATION

DEWDEW FOGFOG CLOUDSCLOUDS

DEPOSITION AND DEPOSITION AND SUBLIMATIONSUBLIMATION

CHANGE FROM CHANGE FROM VAPOR DIRECTLY VAPOR DIRECTLY TO SOLIDTO SOLID

FROSTFROST

CHANGE FROM CHANGE FROM SOLID DIRECTLY SOLID DIRECTLY TO A VAPORTO A VAPOR

SNOWBANK SNOWBANK MELTINGWITH MELTINGWITH FREEZING REMPSFREEZING REMPS

DEPOSITION (Heat released)

FREEZING CONDENSATION

MELTING EVAPORATION

LIQUID WATER(clouds, rain, dew)

ICE(snow, hail, frost)

WATER VAPOR(invisible)

SUBLIMATION (Heat absorbed)

Heat released

Heat absorbed

HUMIDITYHUMIDITY

AMT OF WATER VAPOR IN THE AIR VARIES AMT OF WATER VAPOR IN THE AIR VARIES WIDELYWIDELY

SPECIFIC HUMIDITYSPECIFIC HUMIDITY IS THE NUMBER OF IS THE NUMBER OF GRAMS OF WATER VAPOR IN A Kg OF AIR GRAMS OF WATER VAPOR IN A Kg OF AIR AT A GIVEN TIME OR LOCATIONAT A GIVEN TIME OR LOCATION WARM AIR CAN HOLD MORE MOISTURE WARM AIR CAN HOLD MORE MOISTURE

THAN COLD AIRTHAN COLD AIR

SATURATED AIR OCCURS WHEN SATURATED AIR OCCURS WHEN EVAPORATION RATE EQUALS EVAPORATION RATE EQUALS CONDENSATION RATE EX. LID ON CUPCONDENSATION RATE EX. LID ON CUP

RELATIVE HUMIDITYRELATIVE HUMIDITY

AMOUNT OF WATER VAPOR IN THE AIR AMOUNT OF WATER VAPOR IN THE AIR COMPARED TO THE AMOUNT THE AIR COMPARED TO THE AMOUNT THE AIR CAN HOLD AT A GIVEN TEMPERATURECAN HOLD AT A GIVEN TEMPERATURE

RH = RH = SPECIFIC HUMIDITYSPECIFIC HUMIDITY X 100 X 100 MAXIMUM CAPACITYMAXIMUM CAPACITY

PSYCHROMETER – MEASURES HUMIDITYPSYCHROMETER – MEASURES HUMIDITY

CONDENSATIONCONDENSATION

THE TEMPERATURE AT WHICH THE TEMPERATURE AT WHICH SATURATION OCCURS AND SATURATION OCCURS AND CONDENSATION BEGINS IS CALLED THE CONDENSATION BEGINS IS CALLED THE DEW POINTDEW POINT

IT IS A MEASURE OF THE AMOUNT OF WATER IT IS A MEASURE OF THE AMOUNT OF WATER VAPOR IN THE AIRVAPOR IN THE AIR

EX. WARM DAY AND COLD NIGHTEX. WARM DAY AND COLD NIGHT

COOLING AND COOLING AND CONDENSATIONCONDENSATION

TWO CONDITIONS NECESSARY FOR TWO CONDITIONS NECESSARY FOR CONDENSATIONCONDENSATION 1. MATERIAL TO CONDENSE ON 1. MATERIAL TO CONDENSE ON

((CONDENSATION NUCLEI SALT, CONDENSATION NUCLEI SALT, SULFATES OR NITRATES)SULFATES OR NITRATES)

2. AIR TEMP AT DEW POINT2. AIR TEMP AT DEW POINT

AIR MAY COOL OR LOSE HEAT AIR MAY COOL OR LOSE HEAT BY:BY:

CONTACT WITH COLDER SURFACECONTACT WITH COLDER SURFACE RADIATION OF HEATRADIATION OF HEAT MIXING WITH COLDER AIRMIXING WITH COLDER AIR EXPANSION AS IT RISESEXPANSION AS IT RISES

FORMATION OF FROST AND FORMATION OF FROST AND DEWDEW

FORM WHEN MOIST AIR CONTACTS FORM WHEN MOIST AIR CONTACTS COOL SURFACES AND DEW POINT COOL SURFACES AND DEW POINT TEMP IS REACHEDTEMP IS REACHED

BELOW 0BELOW 000C = FROSTC = FROST

FORMATION OF FOG / FORMATION OF FOG / CLOUDSCLOUDS

FORM WHEN A COLD FORM WHEN A COLD SURFACE CONTACTS SURFACE CONTACTS WARMER MOIST AIRWARMER MOIST AIR

THE SLIGHTEST AIR THE SLIGHTEST AIR MOVEMENTS KEEP MOVEMENTS KEEP THE TINY DROPLETS THE TINY DROPLETS OF WATER OF WATER SUSPENDED SUSPENDED

RADIATION FOGRADIATION FOG(DO NOT WRITE)(DO NOT WRITE)

FORMS WHEN THE FORMS WHEN THE NIGHT SKY IS CLEAR NIGHT SKY IS CLEAR

GROUND LOSES HEAT GROUND LOSES HEAT RAPIDLYRAPIDLY

LIGHT WINDS MIX LIGHT WINDS MIX COOLER BOTTOM AIR COOLER BOTTOM AIR WITH WARMER TOP AIRWITH WARMER TOP AIR DEW POINT IS REACHEDDEW POINT IS REACHED FOG IS COLDER THAN FOG IS COLDER THAN

AIR ABOVE ITAIR ABOVE IT TEMPERATURE TEMPERATURE

INVERSIONINVERSION

ADVECTION FOGADVECTION FOG(DO NOT WRITE)(DO NOT WRITE)

FORM WHEN WARM MOIST AIR FORM WHEN WARM MOIST AIR BLOWS OVER A COOL SURFACEBLOWS OVER A COOL SURFACE

IN U.S. AND CANADA, FORM WHEN IN U.S. AND CANADA, FORM WHEN WARM MOIST SOUTHERLY WIND WARM MOIST SOUTHERLY WIND MOVES OVER SNOW COVERED MOVES OVER SNOW COVERED GROUNDGROUND NEWFOUNDLAND FOGNEWFOUNDLAND FOG WINTER FOGS - MISSISSIPPIWINTER FOGS - MISSISSIPPI