PRECIPITATION                 Prepared by: SUZILAWATIE BT ABDUL GHANI                     P 60832
Characteristics of Precipitation in India     Measurement of Precipitation
CLIMATE                                              2 transitional                2 major seasons                        ...
South – West Monsoon ( June – September )                         Principal rainy season in INDIA            75 % of the a...
South – West Monsoon ( June – September )                               • Monsoon wind across the country in 2            ...
South – West Monsoon ( June – September )                                       • Monsoon wind across the country in 2    ...
South – West Monsoon ( June – September )                                    • Marked by substantial rainfall             ...
South – West Monsoon ( June – September )             Not a period with continuous rainfallMO                Generaly, clo...
South – West Monsoon ( June – September )200–400cm >> Assam          >> North-Eastern200–300cm >> West Coast          >> W...
Post - Monsoon ( October – November )                                 A North-Easterly                  The air massLow pr...
Winter Season ( December – February )                                          Moderate to heavy rain and                 ...
Summer – Pre Monsoon ( March – May )                  Very little rainfall    Convective cells                 >> Kerala  ...
Annual            Rainfall    High rainfall of the magnitude of 200     cm >> Assam >> north-eastern part               >>...
Rainfall                          Snowfall      Non-recording Gauge                Depth of Snowfall      Recording Gauges...
Rainfall            Raingauge is used to collect and measure the precipitation            Pluviometer , ombrometer and h...
`                         Rainfall (Non-Recording Gauges)Circular collecting areawith diameter 12.7 cmFunnel disharge the...
Rainfall (Recording Gauges)Produce a continuous plot of rainfall against timeProvide valuable data of intensity and dura...
Rainfall (Recording Gauges)Tipping-bucket   Weighing-bucket               Natural-Syphon
Rainfall (Recording Gauges)Rainfall of 53.8 mm in 30 hr
Rainfall (Telemetering Raingauges)Recording type and contain electronic unit to transmit the data of rainfall             ...
SnowfallForm of precipitation accumulate over a surface for sometime before it melts and                                  ...
Snowfall (Water Equivalent of Snow)Depth of water that result in melting of a unit of snowImpotant : to assess the seaso...
Snowfall (Water Equivalent of Snow)              A large cylindrical receiver                     A set of telescopic meta...
THANK YOU        NEXT
Chapter 2 Precipitation
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Chapter 2 Precipitation

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Chapter 2 Precipitation

  1. 1. PRECIPITATION Prepared by: SUZILAWATIE BT ABDUL GHANI P 60832
  2. 2. Characteristics of Precipitation in India Measurement of Precipitation
  3. 3. CLIMATE 2 transitional 2 major seasons periodsSouth-west Transition-I Winter Transition-II monsoon ( post season ( summer ) monsoon ) • June - • October - • December • March - September November – February May
  4. 4. South – West Monsoon ( June – September ) Principal rainy season in INDIA 75 % of the annual rainfall is received over a major portionPopularly known “MONSOON” of the country Principal source of rain July - month with has maximum rain Heralds its appearance High south- Originates in in the westerly the Indian southern winds at ocean part or speed 30-70 Kerala kmph (end of May)
  5. 5. South – West Monsoon ( June – September ) • Monsoon wind across the country in 2 branches : >> the Arabian sea >> the Bay of Bengal • 1st week of June >> Southern part of Kerala >> Latter at Assam • The Bay >> north-eastern region >> westwards to Bihar and UP • The Arabian >> northwards – Karnakata, Maharashta and Gujerat • 4th week of June – both branches reach Delhi • Monsoon Trough >> low pressure region >>formed between 2 branches • Monsoon wind increase from June to July and begin to weak in September
  6. 6. South – West Monsoon ( June – September ) • Monsoon wind across the country in 2 branches : >> the Arabian sea >> the Bay of BengalNew • 1st week of June >> Southern part of Kerala >> Latter at AssamDelhi • The Bay >> north-eastern region >> westwards to Bihar and UP • The Arabian >> northwards – Karnakata, Maharashta and Gujerat • 4th week of June – both branches reach Delhi • Monsoon Trough >> low pressure region >>formed between 2 branches • Monsoon wind increase from June to July and begin to weak in September
  7. 7. South – West Monsoon ( June – September ) • Marked by substantial rainfall activity • Start in September • Northern part
  8. 8. South – West Monsoon ( June – September ) Not a period with continuous rainfallMO Generaly, cloudy with frequentN spell of rainfallSO Heavy rainfall >> passage of lowO pressure regionN The bay of Bengal >>Depressions formed >>Frequency 2-3 per month >>Cause excessive precipitation200–400cm >> Assam >> North-Eastern200–300cm >> West Coast >> Western Ghats120–160cm >> West Bengal100–120cm >> UP,Haryana,Punjab
  9. 9. South – West Monsoon ( June – September )200–400cm >> Assam >> North-Eastern200–300cm >> West Coast >> Western Ghats120–160cm >> West Bengal100–120cm >> UP,Haryana,Punjab
  10. 10. Post - Monsoon ( October – November ) A North-Easterly The air massLow pressure area flow of air that pick strikes the eastform in the Bay of up moisture in the coast of the Bengal Bay of Bengal is southern formed peninsula >> cause rainfall Tropical >> The Bay of Bengal November cyclone >> The Arabian Sea Strike the coastal area cause : Intense rainfall Heavy damage Life Property
  11. 11. Winter Season ( December – February ) Moderate to heavy rain and snowfall (about 25 cm) in Himalaya, Jammu and KashmirWestern Disturbance >> Mid December Light rainfall occur in Northern plains >> Disturbances ofextra tropical origin travel eastwards 10-12cm of rainfall in the southern part of Tamil Nadu
  12. 12. Summer – Pre Monsoon ( March – May ) Very little rainfall Convective cells >> Kerala cause >> West Bengal thunderstorms >> Assam Cyclone >> East Coast
  13. 13. Annual Rainfall High rainfall of the magnitude of 200 cm >> Assam >> north-eastern part >> western ghat Scanty rainfall >> eastern Rajasthan >> part of Gujerat, Maharashta and Karnataka Average annual rainfall = 117 cm Coefficient of variation Cv = 100 x standard deviation meanAnnual rainfall varies between 15and 70 from place to placeAverage value of about 30
  14. 14. Rainfall Snowfall Non-recording Gauge Depth of Snowfall Recording Gauges Water Equivalent of Snow Tipping-bucket type Snow Gauges Weighing-bucket type Snow tubes Natural-syphon type Telemetering Raingauges Radar Measurement of Rainfall
  15. 15. Rainfall Raingauge is used to collect and measure the precipitation Pluviometer , ombrometer and hyetometer also used as a raingauge The ground must be level and in the open and its instrument must present a horizontal catch surface Cylindrical-vessel assembly kept in The gauge must be set as near open to collect rain the ground as possible toRaingauge reduce wind effects but must be sufficiently high to prevent The rainfall catch of the raingauge splashing or flooding is affected by it exposure condition The instrument must be surround by an open fenced For setting a raingauge area of at least 5.5 m x 5.5 m. No object should be nearer to the instrument than 30 m or twice the height of the obstruction
  16. 16. ` Rainfall (Non-Recording Gauges)Circular collecting areawith diameter 12.7 cmFunnel disharge therainfall catch into a The rim of the receiving vessel collector is set in a horizontal plane at a height of 30.5 cmFunnel and receiving above the groundvessel are housed in level metalic containerMeasure by a suitablegraduated measuring Proper care, maintenance glass (accuracy = and inspection :- 0.1mm) Especially during dry weather to keep the instrument free from dust and dirt
  17. 17. Rainfall (Recording Gauges)Produce a continuous plot of rainfall against timeProvide valuable data of intensity and duration of rainfall for hydrological analysis of stormTipping-bucket Weighing-bucket Natural-Syphon A 30.5 cm size raingauge Catch from funnel empties Known as float type gauge into a bucket mounted on Catch from funnel bucket weighing scale Collected by funnel-shaped Rainfall collect in a bucket Weight of the bucket and its collector is led into a float tip and bring the other contents are recorded on a chamber causinga float to one position clock-work driven chart rise collected in a storage can A pen through lever system The clockwork has the records the elevation of the  measure to provide the capability to run one week total rainfall and serve a elevation on a rotating drum check driven by a clock-work mechanism The tipping actuates an This instrument gives a plot electricity driven pen to of the accumulated rainfall A syphon arrangement trace a record on clockwork- against the elapsed time  empties the float chamber driven chart the mass curve of rainfall when the float has reached the pre-set max level Ideally suited for digitalizing of the output signal
  18. 18. Rainfall (Recording Gauges)Tipping-bucket Weighing-bucket Natural-Syphon
  19. 19. Rainfall (Recording Gauges)Rainfall of 53.8 mm in 30 hr
  20. 20. Rainfall (Telemetering Raingauges)Recording type and contain electronic unit to transmit the data of rainfall to a base stationUse in gathering rainfall data from >> mountainous >> inaccessible places Rainfall (Radar Measurement of Rainfall) Consider as a remote sensing super gauge For measuring the areal extent, location and movement of rain storms Advantages :- determine amount of rainfall over large areas Operate with wavelenghts from 3 to 10 cm Heavy flood  10 cm radar Light rain and snow  5 cm radar
  21. 21. SnowfallForm of precipitation accumulate over a surface for sometime before it melts and cause runoff Snowfall (Depth of Snowfall) Indicator : useful A graduated for seasonal stick or staff is SNOW BOARDS precipitation and used to measure long term- runoff the depth of snow at a >> Place horizontally on a forecast previous accumulation of snow selected place >> After the snow event, the A snow stakes Snow boards – snow samples are cut off are permanent posts used to 40 cm side >> The depth of snow and water measure the square boards equivalent of snow are derived total depth of >> collect snow and record snow at a place sample
  22. 22. Snowfall (Water Equivalent of Snow)Depth of water that result in melting of a unit of snowImpotant : to assess the seasonal water resource of a catchment in estimates >> stream flow >> flood DENSITY OF SNOW Freshly fallen snow = range of 0.07 to 0.15 Compaction snow = 0.4 to 0.6 Specific data not avaiable = assume 0.10
  23. 23. Snowfall (Water Equivalent of Snow) A large cylindrical receiver A set of telescopic metal tube - 203 mm in diameter - normal size = 40 mm dia - from 60 cm in height - higher size = up to 90 mm dia Windshield is provided at the top Provided with a cutter edge for easy penetration to enableSnow Gauges Snow Tubes extracting of core sample Melting agents or heating system to reduce the size of container To extract the sample, the sample is driven into the snow The snow collected is brought in deposit till it reaches the bottom to a warm room and the snow of deposit and twisted and melted by adding a pre-measured turned to a cut a core quantity of hot water The core is extracted and studied Through volume measurement, for its physical properties and the result is ascertained and melted to obtain water recorded equivalent of the snow core
  24. 24. THANK YOU NEXT
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