WEATHER IS THE MOVEMENT OF AIR MASSES DRIVEN BY THE

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Transcript WEATHER IS THE MOVEMENT OF AIR MASSES DRIVEN BY THE

'Some people would rather die than think and usually do'.
Bertrand Russell
'If we always do what we've always done, we will get what we've
always got.' Adam Urbanski
WEATHER IS THE MOVEMENT OF AIR MASSES
DRIVEN BY THE SUN.
EACH OF THESE AIR MASSES ARE AT DIFFERENT
TEMPERATURES AND CONTAIN DIFFERENT
AMOUNTS OF MOISTURE.
ONE AIR MASS WILL INFLUENCE AND BE
INFLUENCED BY OTHER AIR MASSES.
IT IS A VERY COMPLEX SYSTEM.
SO COMPLEX THAT CHAOS THEORY TALKS
ABOUT THE “BUTTERFLY EFFECT.”
ALL WEATHER TAKES PLACE IN THE TROPOSPHERE.
THE TROPOSPHERE IS 10 TO 14 KM HIGH.
IT CONTAINS ABOUT 75% OF THE MASS OF THE
ATMOSPHERE AND 99% OF THE WATER VAPOR.
THE SUN PROVIDES THE ENERGY.
BUT THE CAUSE IS UNEVEN HEATING OF THE EARTH’S
SURFACE. THE SURFACE IS HEATED UNEVENLY FOR
THREE REASONS:
1.TILT OF THE EARTH ON ITS AXIS.
2.NIGHT ON ONE SIDE AND DAY ON THE OTHER.
3.DIFFERENT SURFACE MATERIALS HEAT AT DIFFERENT
RATES.
THIS ENERGY IS NOT EQUALLY DISTRIBUTED OVER THE
SURFACE OF THE EARTH.
THE EARTH’S AXIS IS TILTED AT 23.5o RELATIVE TO OUR
ORBIT ABOUT THE SUN.
THIS GIVES US OUR SEASONS.
DIFFERENTIAL
HEATING ALSO
LEADS TO
WINDS AND
WIND
PATTERNS ON
BOTH A LOCAL
AND A GLOBAL
LEVEL.
CORIOLIS
EFFECT CAUSES
WINDS TO BEND
TO THE RIGHT IN
THE NORTHEN
HEMISPHERE
AND TO THE
LEFT IN THE
SOUTHERN
HEMISPHERE.
WHAT IS THE ATMOSPHERE?
THE LAYER OF GASES SURROUNDING THE EARTH AND
HELD BY GRAVITY.
THE ATMOSPHERE SUPPORTS LIFE ON EARTH.
IT ABSORBS SOLAR RADIATION .
IT PROTECTS US FROM HIGH ENERGY RADIATION AND
THE FRIGID VACUUM OF OUTER SPACE.
IT TRANSFERS HEAT FROM WARM AREAS TO COLDER
AREAS.
NOTE: IT’S NOT VERY THICK. IF YOU HAD A CAR THAT
WOULD GO STRAIGHT UP, YOU COULD BE IN SPACE IN AN
HOUR.
THE COMPOSITION OF THE
ATMOSPHERE IS:
78%
NITROGEN
21%
OXYGEN
1%
0.038%
ARGON
CARBON DIOXIDE
THIS COMPOSITION IS KEPT IN
BALANCE BY LIFE ON EARTH.
IT HAS VARIED OVER GEOLOGIC
TIME.
OTHER IMPORTANT GASES ARE
WATER VAPOR AND OZONE.
THE AMOUNT OF WATER VAPOR
WILL VARY WITH TEMPERATURE.
AS THE TEMPERATURE
INCREASES, THE AIR CAN HOLD
MORE WATER VAPOR.
THE NORMAL MOLECULAR FORM OF OXYGEN IS O2.
OZONE IS A LESS STABLE FORM OF OXYGEN, AND ITS
FORMULA IS O3.
IN THE STRATOSPHERE, OZONE ABSORBS HARMFUL
UV RADIATION.
IF THE OZONE LAYER DID NOT EXIST, LIFE AS WE
KNOW IT COULD NOT EXIST.
HOWEVER, OZONE IS VERY REACTIVE.
OZONE AT GROUND LEVEL IS DANGEROUS.
LAYERS OF THE ATMOSPHERE
BASED ON HOW THE TEMPERATURE CHANGES, THE ATMOSPHERE IS
DIVIDED INTO LAYERS.
TROPOSPHERE - 75% OF THE MASS OF THE
ATMOSPHERE IS IN THE TROPOSPHERE.
IT EXTENDS FROM EARTH’S SURFACE UP TO ABOUT
10 KM.
ABOVE THIS IS A LAYER WHERE THE TEMPERATURE
IS RELATIVELY CONSTANT - THE TROPOPAUSE.
THE JET STREAM, A FAST MOVING WIND CURRENT,
OCCURS IN THE TROPOPAUSE.
THE STRATOSPHERE IS THE LAYER ABOVE THE
TROPOPAUSE.
THE OZONE LAYER IS IN THE STRATOSPHERE,
WHICH CAUSES THE TEMPERATURE INCREASE.
THE STRATOSPHERE EXTENDS UP TO ABOUT 50 KM.
ABOVE THE STRATOSPHERE IS A THIN LAYER CALLED
THE STRATOPAUSE WHERE THE TEMPERATURE IS
CONSTANT.
ABOVE THIS IS THE MESOSPHERE, WHERE THE
TEMPERATURE DECREASES AGAIN TO -100o C.
THIS IS BECAUSE THERE IS NO CONCENTRATED LAYER
OF OXONE.
THE MESOSPHERE GOES FROM ABOUT 50 KM UP TO 80
KM.
METEOROIDS USUALLY BURN UP IN THIS LAYER.
THE THERMOSPHERE IS ABOVE THE MESOPAUSE.
IN THIS LAYER, THE AIR HEATS UP BECAUSE OF RADIATION.
THIS LAYER GOES FROM 80 KM UP.
IT CONTAINS THE MAGNETOSPHERE - EARTH’S MAGNETIC
FIELD.
THE AURORAS OCCUR HERE.
Earth’s atmosphere exerts pressure
on us.
At sea level, the pressure is 14.7
lb/in2.
It is due to the force of gravity on
the column of air above us.
Why don’t we notice it?
IF YOU WERE ON A MOUNTAIN, WOULD THE
WEIGHT OF THE AIR ABOVE YOU (AIR
PRESSURE) BE GREATER THAN OR LESS
THAN IT IS NOW?
PRESSURE = FORCE (weight) / AREA
OUR UNITS ARE USUALLY:
POUNDS / IN.2 (pounds per square inch)
Or
MILLIBARS
Or
INCHES OF MERCURY
1 ATMOSPHERE (pressure at sea level) = 14.7 psi =
1013.25 millibars = 760 mmHg = 29.92 in Hg
A BAROMETER IS USED
TO MEASURE AIR
PRESSURE.
SATELLITE DISTANCES – 200 TO 500 MILES
- GEOSYNCHRONOUS AT 23,000 MI
- HUBBLE SPACE TELESCOPE, 600
MI