Climate

Kolkata has a tropical wet-and-dry climate (Koppen climate classification Aw). The annual mean temperature is 26.8 °C (80.2 °F); monthly mean temperatures range from 19 °C (66.2 °F) to 30 °C (86.0 °F).^[35] Summers are hot and humid with temperatures in the low 30's and during dry spells the maximum temperatures often exceed 40 °C (104 °F) during May and June.^[35] Winter tends to last for only about two and a half months, with seasonal lows dipping to 9 °C – 11 °C (54 °F – 57 °F) between December and January. The highest recorded temperature is 43.9 °C (111.0 °F) and the lowest is 5 °C (41.0 °F).^[35]On an average, May is the hottest month with daily temperatures ranging from a low of 27 °C (80.6 °F) to a maximum of 37 °C (98.6 °F),while January the coldest month has temperatures varying from a low of 12 °C (53.6 °F) to a maximum of 23 °C (73.4 °F). Often during early summer, dusty squalls followed by spells of thunderstorm or hailstorms and heavy rains with ice sleets lash the city, bringing relief from the humid heat. These thunderstorms are convective in nature, and is locally known as Kal baisakhi (কালবৈশাখী, Nor'westers).^[36]

Rains brought by the Bay of Bengal branch of South-West monsoon^[37] lash the city between June and September and supplies the city with most of its annual rainfall of 1,582 mm (62 in). The highest rainfall occurs during the monsoon in August—306 mm (12 in)). The city receives 2,528 hours of sunshine per annum, with the maximum sunlight occurring in March.^[38] Pollution is a major concern in Kolkata, and the Suspended Particulate Matter (SPM) level is high when compared to other major cities of India,^{[39][40][dead links]} leading to regular smog and haze. Severe air pollution in the city has caused rise in pollution-related respiratory ailments such as lung cancer.^[41]

Geography

Kolkata is located in eastern India at 22°33′N, 88°20′E in the Ganges Delta at an elevation ranging between 1.5 m (5 ft) to 9 m (30 ft).^[27] It is spread linearly along the banks of the River Hooghly in a north-south direction. Much of the city was originally a vast wetland, reclaimed over the decades to accommodate the city's burgeoning population.^[28] The remaining wetland, known as East Calcutta Wetlands has been designated a "wetland of international importance" under the Ramsar Convention.^[29]

Like the most of the Indo-Gangetic plains, the predominant soil type is alluvial. Quaternary sediments consisting of clay, silt, various grades of sand and gravel underlie the city. These sediments are sandwiched between two clay beds, the lower one at depths between 250 m (820 ft) and 650 m (2,133 ft) and the upper one ranging between 10 m (33 ft) and 40 m (131 ft) in thickness.^[30] According to the Bureau of Indian Standards, the town falls under seismic zone-III, in a scale of I to V (in order of increasing proneness to earthquakes)^[31] while the wind and cyclone zoning is "very high damage risk", according to UNDP report.^[31]

About Kolkata

Kolkata (help·info) (Bengali: কলকাতা), IPA: ['kolkat̪a], formerly Calcutta (help·info), is the capital of the Indian state of West Bengal. It is located in eastern India on the east bank of the River Hooghly. When referred to as "Kolkata", it usually includes the suburbs, and thus its population exceeds 15 million, making it India's second-largest city and urban agglomeration.

Kolkata served as the capital of India during the British Raj until 1911. Once the centre of modern education, industry, science, culture and politics in India, Kolkata witnessed intense political violence, clashes and economic stagnation from the years starting 1954 and continuing till this day. However, since the year 2000, economic rejuvenation has led to a spurt in the city's growth. Like the other metropolitan cities of India, Kolkata continues to struggle with urbanisation problems like poverty, pollution and traffic congestion.

Kolkata is noted for its revolutionary history, ranging from the Indian struggle for independence to the leftist and trade union movements.