PRESENTED BY:RAKHI DEVRASHMI RVENKATESHSUNIDHI MADHAVSWATHE SIVAGAMI. YSOUMYA NAYAKSONALI

III SEM C-Section

CLIMATIC ZONES OF INDIA:

Hot and DryWarm and HumidCompositeTemperateCold

3 Main Cities with WARM AND HUMID CLIMATE:

ChennaiKolkataMumbai

NOTE : All the 3 cities are coastal areas

CHENNAI Chennai has a tropical wet and dry climate (Köppen:Aw). The

city lies on the thermal equator and is also on the coast, which prevents extreme variation in seasonal temperature. The hottest part of the year is late May to early June, known regionally as Agni Nakshatram ("fire star") or as Kathiri Veyyil, with maximum temperatures around 35–40 °

The thermal equator (also known as "the heat equator") is a belt encircling the Earth, defined by the set of locations having the highest mean annual temperature at each longitude around the globe.

The city gets most of its seasonal rainfall from the north–east monsoon winds, from mid–October to mid–December. Cyclones in the Bay of Bengal sometimes hit the city.

Prevailing winds in Chennai are usually southwesterly between April and October[ and northeasterly during the rest of the year.

Temperature

Over the course of a year, the temperature typically varies from 21°C to 38°C and is rarely below20°C or above 41°C.

Daily High and Low Temperature:The daily average low (blue) and high (red) temperature with percentile bands (inner band from 25th to 75th percentile, outer band from 10th to 90th percentile).

Fraction of Time Spent in VariousTemperature Bands

The average fraction of time spent in various temperature bands: frigid (below -9°C), freezing (-9°C to 0°C), cold (0°C to 10°C), cool (10°C to 18°C), comfortable (18°C to 24°C), warm (24°C to 29°C), hot (29°C to 38°C) and sweltering (above 38°C).

Daily Hours of Daylight and Twilight

The number of hours during which the Sun is visible (black line), with various degrees of daylight, twilight, and night, indicated by the colorbands. From bottom (most yellow) to top (most gray

Daily Sunrise & Sunset with Twilight

The solar day over the course of the year 2012 . From bottom to top, the black lines are the previous solar midnight, sunrise, solar noon, sunset, and the next solar midnight. The day, twilights (solar, civil, nautical, and astronomical), and night are indicated by the color bands from yellow to gray.

CLOUDSThe median cloud cover ranges from 38% (mostly clear) to 79% (partly cloudy). The sky is cloudiest on July 26 and clearest on February 29. The clearer part of the year begins around December 4. The cloudier part of the year begins around May 31.

MEDIAN CLOUD COVER The median daily cloud cover (black line) with percentile bands (inner band from 40th to 60th percentile, outer band from 25% -75%).

CLOUD COVER TYPES

The fraction of time spent in each of the five sky cover categories. From top (most blue) to bottom (most gray), the categories are clear, mostly clear, partly cloudy, mostly cloudy, and overcast. Pink indicates missing data. Outside of the United States clear skies are often reported ambiguously, leading them to be lumped in with the missing data.

PROBABILITY OF PRECIPITATION AT SOME POINT IN THE DAY

The fraction of days in which various types of precipitation are observed. If more than one type of precipitation is reported in a given day, the more severe precipitation is counted. The order of severity is from the top down in this graph, with the most severe at the bottom.

PRECIPITATION The most common forms of precipitation are thunderstorms,

drizzle, moderate rain, and light rain. Thunderstorms are the most severe precipitation observed

during 32% of those days with precipitation. They are most likely around October 8, when it is observed during 23% of all days.

Drizzle is the most severe precipitation observed during 29% of those days with precipitation. It is most likely around July 28, when it is observed during 19% of all days.

Moderate rain is the most severe precipitation observed during 21% of those days with precipitation. It is most likely around November 21, when it is observed during 15% of all days.

Light rain is the most severe precipitation observed during 16% of those days with precipitation. It is most likely around July 21, when it is observed during 10% of all days.

snow is exceptionally unlikely to fall at any time during the year at this location or this station does not reliably report precipitation types.

Warm Season PrecipitationDuring the warm season, which lasts from April 30 to June 18, there is a 25% average chance that precipitation will be observed at some point during a given day. When precipitation does occur it is most often in the form of thunderstorms (38% of days with precipitation have at worst thunderstorms), drizzle (31%), moderate rain (16%), and light rain (14%).

Cold Season PrecipitationDuring the cold season, which lasts from October 26 to February 9, there is a 31% average chance that precipitation will be observed at some point during a given day. When precipitation does occur it is most often in the form of moderate rain (29% of days with precipitation have at worst moderate rain), drizzle (27%), thunderstorms (24%), and light rain (17%).

HUMIDITY The relative humidity typically ranges

from 39% (comfortable) to 95% (very humid) over the course of the year, rarely dropping below 28% (dry) and reaching as high as 100% (very humid).

The air is driest around May 23, at which time the relative humidity drops below 45% (comfortable) three days out of four; it is most humid around October 30, exceeding 94% (very humid) three days out of four.

RELATIVE HUMIDITY

The average daily high (blue) and low (brown) relative humidity with percentile bands (inner bands from 25th to 75th percentile, outer bands from 10th to 90th percentile).

DEW POINT Dew point is often a better measure of how

comfortable a person will find the weather than relative humidity because it more directly relates to whether perspiration will evaporate from the skin, thereby cooling the body. Lower dew points feel drier and higher dew points feel more humid.

Over the course of a year, the dew point typically varies from 18°C (mildy humid) to 27°C (very oppressive) and is rarely below 14°C (comfortable) or above 28°C (very oppressive).

The daily average low (blue) and high (red) dew point with percentile bands (inner band from 25th to 75th percentile, outer band from 10th to 90th percentile).

WIND Over the course of the year typical wind speeds vary

from 0 m/s to 7 m/s (calm to moderate breeze), rarely exceeding 9 m/s (fresh breeze).

The highest average wind speed of 4 m/s (gentle breeze) occurs around May 27, at which time the average daily maximum wind speed is 7 m/s (moderate breeze).

The lowest average wind speed of 2 m/s (light breeze) occurs around October 30, at which time the average daily maximum wind speed is 5 m/s (gentle breeze).

WIND SPEED

The average daily minimum (red), maximum (green), and average (black) wind speed with percentile bands (inner band from 25th to 75th percentile, outer band from 10th to 90th percentile).The wind is most often out of the south (11% of the time) and west (10% of the time). The wind is least often out of the north west (3% of the time) and north (4% of the time).

WIND DIRECTIONS OVER THE ENTIRE YEAR

The fraction of time spent with the wind blowing from the various directions over the entire year. Values do not sum to 100% because the wind direction is undefined when the wind speed is zero.

Fraction of Time Spent with Various Wind Directions

The fraction of time spent with the wind blowing from the various directions on a daily basis. Stacked values do not always sum to 100% because the wind direction is undefined when the wind speed is zero.

GEOLOGY The geology of Chennai comprises

mostly clay, shale and sandstone. The city is classified into three regions based on geology, sandy areas, clayey areas and hard-rock areas. Sandy areas are found along the river banks and the coasts. Clayey regions cover most of the city.

In sandy areas such as and the rest of coastal Chennai, rainwater run-off percolates very quickly. In clayey and hard rock areas, rainwater percolates slowly, but it is held by the soil for a longer time.

MUMBAI

Mumbai receives pretty heavy rainfall through the Southwest Monsoon winds, which start in mid June.

The rainfall quells the heat a little.

The average temperature falls from 30 to 25 over the next three months. The rainfall lasts till September.

With a brief stint of heat in October, the 'on paper' winter starts in November. Thus the temperatures in Mumbai are comparatively bearable from June to December.

Chennai receives rainfall (much lower than Mumbai) predominantly through the North East Monsoon winds which start only in mid September and last till December.

This makes the months of June, July and August as unbearable as summer in terms of temperature.

This quarter of the year is what differentiates the climate of the two cities.

CHENNAI

SOUTHWEST MONSOONThe southwestern summer monsoons occur from July through September.This causes a low pressure area over the northern and central Indian subcontinent. To fill this void, the moisture-laden winds from the Indian Ocean rush in to the subcontinent.These winds, rich in moisture, are drawn towards the Himalayas. The Himalayas act like a high wall, blocking the winds from passing into Central Asia, and forcing them to rise. As the clouds rise their temperature drops and precipitation occurs.

The southwest monsoon is generally expected to begin around the beginning of June and fade away by the end of September. The moisture-laden winds on reaching the southernmost point of the Indian Peninsula, due to its topography, become divided into two parts: theArabianSea Branch and the Bay of Bengal Branch.

The Arabian Sea Branch of the Southwest Monsoon first hits the Western Ghats of the coastal state of Kerala, India, thus making this area the first state in India to receive rain from the Southwest Monsoon.

The Bay of Bengal Branch of Southwest Monsoon flows over the Bay of Bengal heading towards North-East India and Bengal, picking up more moisture from the Bay of Bengal.

Certain regions of India like Assam and West Bengal, also frequently experience heavy floods during this season

NORTHEAST MONSOON Around September, with the sun fast retreating south, the northern land mass of the Indian subcontinent begins to cool off rapidly.

With this air pressure begins to build over northern India, the Indian Ocean and its surrounding atmosphere still holds its heat.

This causes cold wind to sweep down from the Himalayas and Indo-Gangetic Plain towards the vast spans of the Indian Ocean south of the Deccan peninsula. This is known as the Northeast Monsoon or Retreating Monsoon.

While travelling towards the Indian Ocean, the dry cold wind picks up some moisture from the Bay of Bengal and pours it over peninsularIndiaand parts of Sri Lanka.

Cities like Chennai, which get less rain from the Southwest Monsoon, receives rain from this Monsoon. About 50% to 60% of the rain received by the state of Tamil Nadu is from the Northeast Monsoon.

In Southern Asia, the northeastern monsoons take place from December to early March when the surface high-pressure system is strongest.

The jet stream in this region splits into the southern subtropical jet and the polar jet. The subtropical flow directs northeasterlywinds to blow across southern Asia, creating dry air streams which produce clear skies over India.

Meanwhile, a low pressure system develops over South-East Asia and Australia and winds are directed toward Australia known as a monsoon trough.

DESIGN FOR WARM AND HUMID ZONES • Provide maximum ventilation and free air movement

by large openings.• Provide maximum shading of direct and diffuse solar radiation.• Avoid heat storage.• Use reflective outer surfaces.• Use ventilated double roofs.• Use vegetation to moderate the solar impact.

SUN ORIENTATION

Settlements should be placed preferably on southern or northern slopes, ideally facing away from the equator. The warm-humid climate zones are generally located near the equator. As a consequence, east and west slopes receive more radiation compared to north and south slopes and are, therefore, disadvantageous.

WIND ORIENTATION

Ideal sites are windward slopes near the crest or near the beach, where regular winds exist. The ventilation effect of winds can be improved by effective arrangement of vegetation. open settlement pattern is the appropriate response to the climate.

To provide sufficient air circulation, buildings should be scattered

Buildings should be separated with large, free spaces between them. This allows airflow which provides ventilation for cooling and a hygienic environment.

On the other hand, the walking distance to public spaces should be minimal and the footpaths shaded.

Groups of buildings should not be built in too compact a manner. Extended settlements, arranged in a line across the prevailing wind direction give low resistance to air movement and are, therefore, the ideal solution.

In cases where settlements consist of several rows of buildings, the houses should be staggered to avoid windshaded buildings in the downwind rows.

Certain species of trees (e.g. rain trees) form an extraordinary outdoor space by creating a canopy effect. They should not be planted too far from each other, so that the crowns form a wide hall-like space, creating a comfortable microclimate.

VENTILATED DOUBLE ROOF