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ENERGY AND THE ATMOSPHERE. METEOROLOGY. THIS UNIT IS ABOUT WEATHER. HOW IT’S DESCRIBED AND MAPPED THE ENERGY INVOLVED WEATHER VARIABLES AFFECTING DAILY CONDITIONS AS YOU LEARN NEW WORDS AND CONCEPTS LOOK AROUND YOU AND THINK ! !.
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ENERGY AND THE ATMOSPHERE METEOROLOGY
THIS UNIT IS ABOUT WEATHER • HOW IT’S DESCRIBED AND MAPPED • THE ENERGY INVOLVED • WEATHER VARIABLES AFFECTING DAILY CONDITIONS • AS YOU LEARN NEW WORDS AND CONCEPTS LOOK AROUND YOU AND THINK! !
TO DESCRIBE WEATHER WE TALK ABOUT ATMOSPHERIC VARIABLES • TEMPERATURE • PRECIPITATION • WIND • HUMIDITY • AIR PRESSURE
WEATHER IS THE INTERRELATIONSHIP OF ATMOSPHERIC VARIABLES • LOCAL • SHORT-TERM CONDITIONS • TROPOSPHERE (THE LOWEST LAYER OF THE ATMOSPHERE)
WHAT’S A WEATHER FORECAST? • AN INFERENCE • SHORT-TERM PREDICTION ABOUT THE INTERACTION OF VARIABLES • TEMPERATURE • HUMIDITY • AIR PRESURE • WINDS
LET’S TAKE A LOOK AT EACH VARIABLETEMPERATURE IS AFFECTED BY: • INTENSITY AND DURATION OF SUN (INSOLATION) • EARTH SURFACES (LAND, WATER, ICE) • ALTITUDE
AIR PRESSURE IS BAROMETRIC PRESSURE • MEASURED IN MILLIBARS OR INCHES OF MERCURY • ON A MAP ISOBARS CONNECT POINTS OF EQUAL AIR PRESSURE
THE WEIGHT OF AIR PUSHING DOWNWARD CREATES AIR PRESSURE. THIS IS AFFECTED BY: • TEMPERATURE AND DENSITY OF THE AIR • ALTITUDE • MOISTURE CONTENT
HUMIDITY IS WATER VAPOR IN THE AIR • SATURATED AIR HAS 100% HUMIDITY • DEWPOINT IS THE TEMPERATURE AT WHICH AIR BECOMES SATURATED • WARM AIR HOLDS MORE MOISTURE SO IT HAS A HIGHER DEWPOINT
WIND IS CAUSED BY DIFFERENCES IN AIR PRESSURE • AIR MOVES FROM HIGH TO LOW PRESSURE • WIND SPEED IS RELATED TO PRESSURE GRADIENTS • ISOBARS CLOSE TOGETHER INDICATE A STEEP PRESSURE GRADIENT: HIGHER WINDS!
ATMOSPHERIC TRANSPARENCY • HOW CLEAR THE ATMOSPHERE IS • AFFECTS RADIATION REACHING EARTH • AEROSOLSSCATTER AND ABSORB RADIATION • PRECIPITATION CLEANS THE ATMOSPHERE
SYNOPTIC WEATHER MAPS SHOW THE BIG PICTURE • ATMOSPHERIC CONDITONS OVER A LARGE AREA • HELPS ANALYZE HOW VARIABLES INTERACT
AIR MASSES ARE LARGE BODIES OF AIR HAVING SIMILAR CONDITIONS • IDENTIFIED BY AVERAGE TEMPERATURE AND MOISTURE CONTENT • DETERMINED BY THEIR SOURCE REGIONS
LOW AND HIGH PRESSURE SYSTEMS • LOWS ARE CYCLONES -SPIRAL INWARD -COUNTERCLOCKWISE • HIGHS ARE ANTICYCLONES • SPIRAL OUTWARD • CLOCKWISE
HIGHS AND LOWS HAVE “TYPICAL“ WEATHER CONDITIONS • LOWS HAVE WARMER TEMPERATURES, CLOUDS AND PRECIPITATION • HIGHS HAVE COOLER TEMPERATURES, CLEAR SKIES AND DRYER AIR
SO WHAT HAPPENS FROM SUNDAY THRU WEDNESDAY, IN TERMS OF WEATHER SYSTEMS?
THE BOUNDARY BETWEEN DIFFERENT AIR MASSES IS CALLED A FRONT • THE INTERFACE CREATES UNSTABLE CONDITIONS • WINDS, PRECIPITATION AND CHANGING CONDITIONS
A WARM FRONT: WARM AIR MEETS COLDER AIR • WARM AIR RISES, COOLS AND MOISTURE CONDENSES • USUALLY ASSOCIATED WITH LONGER PERIODS OF RAIN
A COLD FRONT OCCURS WHEN COLDER AIR PUSHES INTO A REGION OF WARMER AIR • USUALLY FASTER MOVING • RESULT IN BRIEF BUT HEAVY PRECIPITATION
AN OCCLUDED FRONT IS AN INTERACTION BETWEEN COOL, COLD AND WARM AIR MASSES • FORCES WARM AIR TO RISE • ASSOCIATED WITH FORMATION OF LOW PRESSURE SYSTEMS • OUR BIG ICE STORM WAS AN OCCLUDED FRONT
AIR MASS TRACKS HAVE PREDICTABLE PATHS • PREVAILING WESTERLIES MOVE WEST TO EaST • TROPICAL AIR MOVES NORTHEAST • POLAR AIR MOVES SOUTH EAST
THE JET STREAM IS ANOTHER INFLUENCE ON OUR WEATHER SYSTEMS • A STRONG CURRENT IN THE UPPER TROPOSPHERE • BLOWS WEST TO EAST • CHARACTERIZED AS A FAST-MOVING RIVER OF AIR
ENERGY AND MOISTURE ARE CONSTANTLY RECYCLED IN THE ATMOSPHERE • EVAPORATION • TRANSPIRATION • EVAPOTRANSPIRATION
EVAPORATION RATE IS AFFECTED BY VARIABLES • TEMPERATURE (ENERGY!) • SURFACE AREA OF THE WATER • HUMIDITY
HUMIDITY IS A MEASURE OF MOISTURE IN THE AIR, IN RELATION TO TEMPERATURE • ABSOLUTE HUMIDITY IS THE ACTUAL AMOUNT OF VAPOR IN THE AIR • RELATIVE HUMDITY IS THE AMOUNT OF MOISTURE IN THE AIR COMPARED TO WHAT IT CAN HOLD AT THAT TEMPERATURE
RELATIVE HUMIDITY AND DEWPOINT CAN BE FOUND WITH A SLING PSYCHROMETER • TWO THERMOMETERS • DRY BULB • WET BULB • “SLING” THEM AROUND AND COMPARE TEMPERATURES
HERE’S HOW IT WORKS: • THE DRY BULB RECORDS AIR TEMPERATURE • THE WET BULB EVAPORATES MOISTURE WHICH RESULTS IN COOLING • THE DIFFERENCE BETWEEN THE TWO TEMPERATURES IS SIGNIFICANT. . .THE GREATER THE DIFFERENCE INDICATES LOWER HUMIDITY
HOW IS ENERGY AND MOISTURE TRANSFERRED IN THE ATMOSPHERE? • DENSITY DIFFERENCES FROM UNEQUAL HEATING. . .CONVECTION CURRENTS • PLANETARY WINDS AND AIR PRESSURE “BELTS” • ADIABATIC TEMPERATURE CHANGES. . . WARMING OR COOLING DUE TO PRESSURE CHANGES
ENERGY AND MOISTURE IS TRANSFERRED BY DENSITY DIFFERENCES IN THE ATMOSPHERE • CREATES CONVECTION CURRENTS • AIR RISES IN ONE PLACE AND FALLS IN ANOTHER • PRODUCES LOW AND HIGH AIR PRESSURE “BELTS” • AIR CONVERGES AND RISES AT EQUATOR AND 60 N/S • AIR DESCENDS AND DIVERGES AT POLES AND 30 N/S
ENERGY IS ALSO TRANSFERRED BY ADIABATIC TEMPERATURE CHANGES • WHEN AIR RISES IT COOLS AND IT WARMS AS IT FALLS • RISING AIR LOWERS THE PRESSURE DUE TO EXPANSION • DESCENDING AIR RAISES THE PRESSURE DUE TO COMPRESSION
CLOUDS FORM DUE TO ADIABATIC COOLING • WARM AIR RISES, COOLS AND EVENTUALLY REACHES DEW POINT • CONDENSATION OR SUBLIMATION CREATES MICROSCOPIC WATER DROPLETS AND ICE CRYSTALS • CONDENSATION NUCLEI (DUST OR SALT) ARE NEEDED FOR DROPLETS TO FORM
CLOUDS FORM AT THE ALTITUDE WHERE AIR TEMPERATURE AND DEWPOINT ARE THE SAME • DROPLETS GROW AND EVENTUALLY BECOME PRECIPITATION • DIFFERENT WEATHER CONDITIONS PRODUCE DIFFERENT CLOUDS • CLOUDS ARE NAMED ACCORDING TO SHAPE AND HEIGHT
BASIC TYPES OF CLOUDS • CUMULUS ARE “HEAP” CLOUDS AT DIFFERENT HEIGHTS, ASSOCIATED WITH DRY SUNNY DAYS • NIMBUS USUALLY PRODUCE RAIN OR SNOW
CLOUDS • CIRRUS ARE HIGH LEVEL WISPY CLOUDS MADE OF ICE CRYSTALS • AIRCRAFT CONTRAILS FORM FROM WATER VAPOR IN THE EXHAUST THAT CONDENSES AND FREEZES
CLOUDS • STRATUS FORM LAYERS ACROSS THE SKY AND OFTEN PRODUCE RAIN OR DRIZZLE • FOG IS A CLOUD RESTING ON THE GROUND
THUNDERSTORMS…THE MOST COMMON SEVERE STORM • THERE ARE THOUSANDS OF THUNDERSTORMS ON EARTH AT ANY GIVEN TIME! • UNSTABLE MOIST AIR RISES QUICKLY • CLOUDS FORM, ENERGY IS RELEASED, THE AIR IS HEATED AND THE STORM DEVELOPS VERTICAL HEIGHT
THUNDERSTORM HAZARDS • LIGHTNING • FLOODING • HAIL • MORE PEOLE ARE KILLED BY LIGHTNING THAN BY HURRICANES AND TORNADOES!
BE SAFE! • GO INSIDE, STAY AWAY FROM WINDOWS • AVOID USING ELECTRICAL APPLIANCES • IF YOU ARE OUTDOORS, AVOID HIGH OBJECTS SUCH AS TREES
OCCUR FROM JUNE THROUGH SEPTEMBER DEVELOP FROM TROPICAL DEPRESSIONS IN LOW LATITUDES OVER WARM WATER MORE MASSIVE THAN MID-LATITUDE LOWS CONDENSATION RELEASES ENERGY THE CENTER “EYE” IS AN AREA OF CALM WITH VIOLENT WINDS AND HEAVY PRECIPITATION DESTRUCTIVE DUE TO LARGE SIZE HURRICANES