atmosphere Flashcards
ATMOSPHERE (DEFINATION)
THE BLANKET OF AIR SURROUNDING THE EARTH.
ONE FINDS DIFFICULT TO BREATH AS HE/SHE GOES UP.
AIR BECOMES THINNER AS ONE GOES UP BECAUSE HALF OF THE TOTAL MASS OF AIR IS CONCENTRATED 5 KM BELOW, TOUCHING THE SURFACE OF EARTH, DUE TO THE STRONG FORCES OF GRAVITY BY EARTH WHICH HOLDS IT CLOSE TO EARTH. THUS, AIR BECOMES THINNER AND LESS DENSER WITH RISE IN ALTITUDE THAT IS WHY ONE FEELS DIFFICULT TO BREATHE AS HE/SHE GOES UP. *LESS AIR IS PRESSING DOWN FROM ABOVE.
FUNCTIONS OF ATMOSPHERE.
- ATMOSPHERE ABSORBS THE HARMFUL ULTRAVIOLET AND INFRARED RAYS OF SUN ( DUE TO PRESENCE OF OZONE LAYER) .
- IT HAS LIFE SUSTAINING GASES LIKE OXYGEN AND NITROGEN WHICH HELPS IN RETAINING THE NECESSARY WARMTH OF EARTH FROM THE SUN AND HELPS IN CIRCULATION OF WATER VAPOUR- THE SOURCE OF RAINFALL.
- CO2 PRESENT IN ATMOSPHERE ABSORBS THE HEAT FROM SUN AND KEEPS THE EARTH WARM AT NIGHT AS IT RETAINS IT.
- AIR HAS WEIGHT AND EXERTS PRESSURE THUS, IT REMAINS IN CONTACT WITH THE LAND AND WATERBODIES. DUE TO THIS PHYSICAL CONTACT CIRCULATION AND EXCHANGE OF GASES TAKES PLACE BETWEEN THEM. DUE TO SUCH PHYSICAL CONTACT, THE SOIL ABSORBS O2 AND N2 FROM THE ATMOSPHERE.
COMPOSITION OF CLEAN DRY SAMPLE OF AIR. -
COMPOSITION -
78 % - N2
21%- O2
REMAINING 1% - CO2,HELIUM, ARGON, H20 VAPOUR E.T.C
WHY O2 AND N2 ARE IMPORTANT FOR LIFE SUSTAINANCE ON EARTH ?
O2- HELPS IN BREATHING, CELLULAR RESPIRATION AND COMBUSTION. WITHOUT RESPIRATION ORGANISMS COULD NOT SURVIVE ON EARTH.
N2- COLOURLESS, TASTELESS INERT GAS WITH NO SMELL. SLOWS DOWN PROCESS OF OXIDATION AND DILUTES OXYGEN. ESSENTIAL FOR ALL LIVING ORGANISMS ON EARTH, PLANTS OBTAIN IT THROUGH SOIL AND ANIMALS OBTAIN IT BY EATING OTHER PLANTS AND ANIMALS.
PROCESS OF PRECIPITATION-
EVAPORATION OF WATER FROM WATER BODIES LIKE RIVERS, LAKES, OCEANS AND SEAS. MAY ALSO BE THROUGHT TRANSPIRATION FROM PLANTS AND RESPIRATION OF ANIMALS. EVAPORATED WATER (WATER VAPOUR) RISE UP IN THE SKY AND CONDENSE AROUND HYGROSCOPIC NUCLEI PRESENT IN LOWER LAYER OF ATMOSPHERE LIKE DUST PARTICLES FROM DUST STORMS, POLLEN GRAINS, ASH FROM METEORITES AND VOLCANIC ERUPTION E.T.C TO FORM WATER DROPLETS WHICH ONCE BECOME TOO HEAVY TO BE SUSPENDED IN AIR FALLS DOWN BACK IN THE FORM OF PRECIPATION (RAIN,SNOW,SLEET,HAIL)
FUNCTIONS OF CONDENSATION NUCLEI -
*PLAYS AN IMPORTANT ROLE IN PRECIPATION AS WATER VAPOURS EVAPORATED CONDENSE AROUND THEM TO FORM WATER DROPLETS.
* SCATTERS SUN’S RADIATION DURING SUNRISE AND SUNSET.
EACH CONCENTRIC LAYERS OF ATMOSPHERE HAVE DIFFERENT DENSITIES. JUSTIFY-
ATMOSPHERE HAS SEVERAL CONCENTRIC LAYERS WHICH HAVE MASS AND EXERTS PRESSURE ON THE LOWER LAYER. THUS, THE LOWER LAYER IS HEAVIER AND MORE DENSER THAN THE UPPER LAYER WHICH IS RELATIVELY THINNER AND LESS DENSER. ADDITIONAL FACT- 90% OF THE AIR MASS IS CONCENTRATED WITHIN A HEIGHT OF ABOUT 20KM ABOVE THE SURFACE OF EARTH.
TROPOSHPERE CHARACTERISTICS-
- HEIGHT VARIES FROM 18 KM FROM EQUATOR TO 8KM FROM POLES.
- 75% OF ATMOSPHERE IS CONCENTRATED IN THE TROPOSPHERE. ITS CONCENTRATION DECREASES AS WE GO UP.
*IT IS ALSO CHARACTERISED FOR THE NORMAL LAPSE RATE. THE AVERAGE DECREASE IN TEMPERATURE BY 1 DEGREE CENTIGRADE FOR EVERY 166M RISE IN ALTITUDE. THIS TEMPERATURE VARIATION IS ALSO RESPONSIBLE FOR TURBULENCES IN THIS LAYER. - AS A RESULT OF THESE TURBULENCES , ALL WEATHER PHENOMENON HAPPENS IN THIS LAYER.
- THE TROPOSHPHERE IS HEATED MORE FROM BELOW THAN FROM ABOVE ( INCOMING SHORT WAVE INSOLATION HAS LESS HEATING EFFECT THAN TERRESTIAL RADIATION)
- UPPER LIMIT OF TROPOSPHERE- TROPOPAUSE.
STRATOSPHERE CHARACTERISITCS-
ABOVE THE TROPOSPHERE-
* HEIGHT IS ABOUT 50 KM FROM SEA LEVEL.
* AIR IN STRATOSPHERE IS COLD AND DRY. THE TEMPERATURE IS CONSTANT ABOUT - 55 DEGREE CELSIUS.
* OZONE LAYER IS GENERALLY FOUND IN THE STRATOSPHERE AT AN ALTITUDE BETWEEN 20KM AND 50KM FROM THE SURFACE OF THE EARTH. IT ABSORBS THE ULTRAVIOLET RAYS OF THE SUN.
* THE TEMPERATURE HERE IS CONSTANT AS THE INCOMING SHORT WAVE INSOLATION RECEIVED FROM THE SUN IS EQUAL TO THE HEAT LOST BY THE STRATOSPHERE . IN HIGHER LEVELS HOWEVER, TEMPERATURE INCREASES WITH HEIGHT.
*THE LOWER LAYER OF ATMOSPHERE HAS A VIRTUAL ABSENCE OF WATER VAPOUR AND THUS NO WEATHER PHENOMENON TAKES PLACE AND TEMPERATURE REMAINS CONSTANT HERE. THUS, IT IS IDEAL FOR FLYING JETS HERE. ( CLOUDS ARE NOT AVAILABLE HERE)
* THE TEMPERATURE STARTS INCREASING FROM THE BASE AT - 60 DEGREE CELSIUS TO 0 DEGREE CELSIUS AT THE STRATOPAUSE (UPPER LIMIT) .
MESOSPHERE CHARACTERISTCS-
ABOVE STRATOSPHERE-
* RISES UPTO AN ALTITUDE OF ABOUT 80KM FROM THE SURFACE OF EARTH.
* THE TEMPERATURE DECREASES WITH HEIGHT IN THIS REGION AND REACHES A MINIMUM OF ABOUT -110 DEGREE CELSIUS AT AN ALTITUDE OF ABOUT 80 KM FROM THE SURFACE OF EARTH NEAR THE MESOPAUSE( UPPER LIMIT) .
*DUE TO REFLECTED SUNLIGHT FROM METEORIC DUST PARTICLES WISPY CLOUDS ARE FOUND IN THIS REGION.
THEMOSPHERE- (A) IONOSPHERE (B) EXOSPHERE
(A) EXTENDS TO A HEIGHT OF ABOUT 400 KM FROM THE SURFACE OF THE EARTH.
* CONTAINS ELECTRICALLY CHARGED PARTICLES CALLED IONS WHICH CREATES A SHEET OF LIGHT DISLAY KNOWN AS ‘AURORA BORIALIS’ IN THE NORTHERN HEMISPHERE AND ‘ AURORA AUSTRALIS’ IN THE SOUTHERN HEMISPHERE.
* THE IONS REFLECT BACK THE RADIO WAVES TO THE SURFACE OF EARTH AND ENABLES WIRELESS COMMUNICATION.
(B)
* LIES BETWEEN THE HEIGHT OF 400KM TO 1500KM ABOVE THE SURFACE OF THE EARTH.
* TEMPERATURE INCREASES WITH HEIGHT. VERY LITTLE IS KNOWN BEYOND THE ALTITUDE OF 640 KM FROM THE SURFACE OF THE EARTH.
* IT MERGES GRADUALLY INTO THE OUTER SPACE.
* IN EXOSPHERE DENSITY BECOMES EXTREMELY LOW.
* MAIN GASES HERE ARE LIGHTER ONES LIKE HELIUM AND HYDROGEN.
HOW RARE IS OZONE?
FOUND IN VERY RARE AMOUNTS IN EARTH’S ATMOSPHERE. ALMOST ONE OUT EVERY 2 MILLION MOLECULES IS OZONE.
HOW O3 IS FORMED IN STRATOSPHERE ? HOW POLLUTANTS DISRUPT THE O3 FORMATION?
HIGH ENERGY RADIATION FROM SUN CONVERTS O2 MOLECULE TO OZONE IN STRATOSPHERE. THE POLLUTANTS PRODUCED FROM HYDROCARBONS EMITTED FROM AUTOMOBILE EXHAUSTS AND JET FUELS COME IN CONTACT WITH THE HIGH ENERGY RADIATED BY SUN WHICH DECREASES THE PRODUCTION OF 03.
WHAT IS AN ‘OZONE HOLE’ ? WHAT CHEMICALS CAUSE DEPLETION OF OZONE?
AN OZONE HOLE IS AN OZONE DEPLETED AREA WHOSE IMAGES ARE CONDUTED BY STAELLITES FROM NASA IN USA. THE CHEMICALS CHLORINE AND BROMINE CAUSE DEPLETION OF OZONE LAYER.
