Cloud, Monsoon and Climate Related Point Wise Notes For Competitive Exam

climate

• Clouds are prominent in summer season.

• Cumulo-nimbus clouds are tremendous towering clouds with a vertical range of 3 to 8 km from base to top.

• Cumulo-nimbus clouds forms thunderstorms.

• Low pressure areas near equator are called doldrums.

• Due to the rotation of earth air in the polar region swung to temperate regions resulting in low pressure in polar region called as polar calms.

• On earth doldrums and polar calms are the two low pressure areas.

• Latitudinal belt between 30 to 35o of both south and north are called horse latitudes.

• Air currents at the upper layers of equator and poles meet at horse latitudes leading to high pressure.

• Due to high temperature at equator air moves upward and creates low pressure area at equator.

• Air from lower layers of atmosphere move from both south and north latitudes to fill the low pressure belt.

• This type of air movements occurring throughout the year are known as trade winds or tropical easterlies.

• Trade winds have same course or track year after year.

• Due to high pressure in upper layers of equator air moves towards south or north in the upper layers. These winds are called antitrade winds.

• Direction of antitrade winds is opposite to trade winds.

• Wind movement in trade winds occurs in the lower layers of atmosphere.

• Wind movement in anti trade winds occurs in upper layers of atmosphere.

• Word monsoon is derived from Arabic term ‘Mausam’ meaning ‘Season’.

• Course of trade winds changes during a year due to local factors like topography, oceans etc.

• Trade winds with changed direction are called monsoon winds.

• Monsoon winds change direction with season.

• India experiences south-west monsoon winds and north-east monsoon winds.

• India is situated in the north-east trade wind zone and these trade winds continue throughout the year.

• South east trade winds start from south of equator, while traveling over Indian ocean they absorb large amounts of moisture and while crossing equator they are caught up suddenly in the air circulation over India and deflected as south-west winds.

• South west monsoon enter into Kerala around June 1st every year.

• South coastal Andhra Pradesh and Tamil Nadu gets sufficient amount of rainfall from North-East monsoon.

• South west monsoon or rainy or monsoon period is from June to September.

• 60% of total rainfall of the year is received during south west monsoon period.

• Tropical climate prevails during south west monsoon period i.e., warm, humid climate.

• North-east monsoon or post rainy season or post monsoon period is from October to December.

• 33% of annual rainfall is received during north east monsoon period.

• Cyclones are called by different names in different countries

North America – Hurricane Typhoon – Eastern Asia, Philippines Baquio – China Cyclone – India, Australia

• Cyclones generally originate in water warmer than 27 °C.

• Centre of cyclone is known as eye.

• Intensive low pressure areas with more or less circular shape are called cyclones.

• Indian Meteorological Department was started in Pune in 1875.

• Observed weather conditions are marked in brief coded form as a synopsis of this conditions and this type of report is known as synoptic report.

• In synoptic charts or weather charts observations recorded at scheduled times are charted on outline map of India using international code of signals and observations.

• Short range weather forecasts are for a day or two.

• Short range weather forecasts are useful for irrigation engineers, mariners, aviation engineers and farmers.

• Medium range forecasts are for a period of 3 to 4 days to two weeks.

• Long range forecasts are for periods of more than four weeks.

• Long range forecasts are useful for choosing crop patterns.

• Application of foreign material to clouds to induce precipitation is called cloud seeding.

• Silver iodide is used for seeding cold clouds.

• Sodium chloride (common salt) is used for seeding warm clouds.

• Soil temperature is increased by planting crops on the sunny wall of furrows.

• Decandole is the first person to attempt classification of climate.

• Decandole classified climate based on vegetation.

• Koppen was the first person to classify climate based on weather elements.

• Trolls climate classification is suitable for agriculture purpose.

• Koppen’s and Thornthwaite’s classifications are most widely accepted.

• Koppen has taken annual and monthly means of temperature and precipitation for classification of climate.

• In tropical climate even the coolest month has average temperature more than 18°C.

• In temperate climate average temperature of coolest month is in the range of 18°C to -3°C.

• In cold climates average temperature of coolest month is less than -3°C.

• In polar climate average temperature of warmest month is less than 10°C.

• Koppen classified climate from A to E.

• Depending on the form of precipitation climate is classified into rainy or snow climate.

• If annual rainfall is less than evaporation then it is called dry climate.

• In Tropical rainy climate (A) average temperature of coolest month greater than 18°C, precipitation in the form of rain, rainfall is more than evaporation.

• In Tropical dry climate (B) average temperature of coolest month is more than 18oC, rainfall is less than evaporation.

• Tropical dry climate (B) is divided into Arid climate (BA) and Semiarid (BS) climate.

• In mild temperate rainy climate (C) average temperature of coolest month is in the range of 18°C to -3°C.

• In Cold snow climate (D) average temperature of coolest month is less than -3°C, precipitation in the form of snow.

• In Polar climate (E) average temperature of warmest month is less than 10°C.

• Polar climate (E) is sub divided into Tundra and Ice cap.

• These classifications (A to E) are again divided into four letter classification. Second letter after capital letter related to seasonal rainfall, third letter refers to annual temperature and four letter relates to specific characteristics. E.g. BSmha i.e., Tropical dry climate (B), semiarid (S), rainfall received during monsoon season (m), average annual temperature is more than 18oC (h) and with a long hot summer (a).

• Most of south India comes under above group.

• Thornthwaite classified climate based on PE index, TE index and seasonal distribution of rainfall.

• Precipitation of effectiveness(PE) index = P/E x 100

P = Annual Precipitation

E = Annual evaporation

• South India climate can be grouped under DA’s in Thornthwaite classification which means semiarid tropical with rainfall deficit in summer.

• Troll classified climate based on temperature and humid months.

• In tropical region mean monthly temperature of coolest month is more than 18°C.

• Tropical region is divided into five groups based on number of humid months.

• In a humid month monthly precipitation exceeds monthly potential evapotranspiration.

• Main drawback of Troll’s classification is continuity of humid months is not considered.

• ICRISAT revised Troll’s classification and developed modified Troll’s classification.

• According to ICRISAT classification 88 per cent of geographical area of India is under tropics.

• Dry semiarid tropics constitute 57 per cent of geographical area of India.

• If the rainfall exceeds twice the normal deviation at a particular place, that year is said to be a wet year.

• Planning commission divided India into 15 agro-climatic zones based on rainfall, temperature, soil, topography, cropping, farming systems and water resources.

• Western plateau and hills zone is the largest agro-climatic zone.

• Western Himalayan zone comprising of three distinct subzones of Jammu and Kashmir, Himachal Pradesh and Uttar Pradesh hills are characterized by skeletal soils of cold region, mountain meadow soils, podsolic soils, hilly brown soils. Lands are having steep slopes with undulating terrain.

• Eastern Himalayan zone is characterized by high rainfall and forest cover.

• Shifting cultivation is practiced in nearly one-third of cultivated area in Eastern Himalayan Zone.

• Lower gangetic plains zone consists of districts of West Bengal, soils are mostly alluvial and prone to floods.

• Middle gangetic plains comprising of districts of UP and Bihar has a cropping intensity of 142% and 39 per cent of gross cropped area is irrigated.

• In upper gangetic plains zone consisting of districts of UP, irrigation is through canals and tube wells.

• Trans-gangetic plains zone consisting of Punjab, Haryana, Union territories of Delhi and Chandigarh and Sriganganagar district of Rajasthan are characterized by highest irrigated area, high cropping intensity and high ground water utilization.

• Eastern Plateau and hills zone comprising of eastern Madhya Pradesh, southern Bengal and inland Odisha is characterized by shallow and medium deep soils, undulating topography, slope of 1 to 10% and irrigation through tanks and tube wells.

• Western plateau and hills zone comprising of most of Maharashtra, part of MP, one district of Rajasthan is characterized by 65% net sown area,11% forests,12.4% irrigated area with canals being the main source.

• Southern plateau and hills zone comprising of Andhra Pradesh, Karnataka and Tamil Nadu characterized by cropping intensity of 111% and dry land farming is adopted in 81% area.

• East coast plains and hills comprise of east coast of Tamil Nadu, Andhra Pradesh and Odisha characterized by alluvial soils and coastal sands and irrigation is through canals and tanks.

• Gujarat plains and hills zone comprising of 19 districts of Gujarat characterized by arid climate with low rainfall, only 32.5 per cent area is irrigated mainly through wells and tube wells.

• Western dry zone comprises of nine districts of Rajasthan characterized by hot sandy desert, erratic rainfall, high evaporation, scanty vegetation. Famine and drought are common features of this region.

• Island zone comprising of island territories of Andaman and Nicobar and Lakshadweep are equatorial with a rainfall of 3000mm, is largely a forest zone with undulated lands.

• India has a coastline of 8129 km.

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