Cherrapunji; currently the historical name Sohra is more commonly used; alternative spellings are Cherrapunjee and Charrapunji), is a subdivisional town in the East Khasi Hills district in the Indian state of Meghalaya. It is credited as being the wettest place on Earth, although nearby Mawsynram currently holds that record. Cherrapunji still holds the all-time record for the most rainfall in a calendar month and in a year: it received 9,300 mm (366 in) in July 1861 and 26,461 mm (1,041.75 in) between 1 August 1860 and 31 July 1861. Cherrapunji is the traditional capital of a hima (Khasi tribal chieftainship constituting a petty state) known as Sohra or Churra.
Cherrapunji has an average elevation of 1,484 metres (4,869 ft) and sits on a plateau in the southern part of the Khasi Hills, facing the plains of Bangladesh. The plateau rises 600 meters above the surrounding valleys. Soils on the plateau are poor owing to deforestation and washout caused by heavy rains. Owing to winter droughts, the vegetation in this location is even xerophytic in spite of the fame of Cherrapunji as an extremely wet place. Additional pressure on local ecosystems is created by the rapid increase of the population — from a Sohra-area population of 7,000 in 1960, it grew to over 100,000 by 2000.
Valleys around Cherrapunji, however, are covered with lush and very diverse vegetation, containing numerous endemic species of plants, including Meghalaya subtropical forests. Yet there is high rainfall in Cherrapunji, there is a high shortage of water. The Shillong Plateau is an uplifted horst-like feature, bounded by the E-W Main Boundary Thrust (MBT) to the North, the N-S Jamuna fault in the west, and the NW-SE kopilli fracture zone in the east.
Cherrapunji has a mild subtropical highland climate (Köppen Cwb), with monsoonal influences typical of India. The city's yearly rainfall average stands at 11,777 millimetres (463.7 in). This figure places it behind only nearby Mawsynram, Meghalaya, whose average is 11,873 millimetres (467.4 in). Cherrapunji receives both the southwest and northeast monsoonal winds, giving it a single monsoon season. It lies on the windward side of the Khasi Hills, so the resulting orographic lift enhances precipitation. In the winter months it receives the northeast monsoon showers that travel down the Brahmaputra valley.
Temperatures average 11.5 °C (52.7 °F) in January and 20.6 °C (69.1 °F) in August, and the annual mean is 17.3 °C (63.1 °F)
It holds two Guinness World records for receiving the maximum amount of rainfall in a single year: 26,471 millimetres (1,042.2 in) of rainfall between August 1860 and July 1861 and for receiving the maximum amount of rainfall in a single month: 9,300 millimetres (370 in) in July 1861.
Causes Of High Rainfall:
Cherrapunji receives rains from the Bay of Bengal arm of the Indian summer monsoon. The monsoon clouds fly unhindered over the plains of Bangladesh for about 400 km. Thereafter, they hit the Khasi Hills which rise abruptly from the plains to a height of about 1370 m above mean sea level within 2 to 5 km. The geography of the hills with many deep valleys channels the low-flying (150–300 m) moisture-laden clouds from a wide area to converge over Cherrapunji. The winds push the rain clouds through these gorges and up the steep slopes. The rapid ascent of the clouds into the upper atmosphere hastens the cooling and helps vapours to condense. Most of Cherrapunji's rain is the result of air being lifted as a large body of water vapour. The extreme amount of rainfall at Cherrapunji is perhaps the best-known feature of orographic rain in northeast India.
Occasionally, cloudbursts can occur in one part of Cherrapunji while other areas may be totally or relatively dry, reflecting the high spatial variability of the rainfall. Atmospheric humidity is extremely high during the peak monsoon period.
The major part of the rainfall at Cherrapunji can be attributed to the orographic features. When the clouds are blown over the hills from the south, they are funneled through the valley. The clouds strike Cherrapunjee perpendicularly and the low flying clouds are pushed up the steep slopes. It is not surprising to find that the heaviest rainfalls occur when the winds blow directly on the Khasi Hills.
A notable feature of monsoon rain at Cherrapunji is that most of it falls in the morning. This could be partly due to two air masses coming together. During the monsoon months, the prevailing winds along the Brahmaputra valley generally blow from the east or the northeast, but the winds over Meghalaya are from the south. These two winds systems usually come together in the vicinity of the Khasi Hills. Apparently the winds that are trapped in the valley at night begin their upward ascent only after they are warmed during the day. This partially explains the frequency of morning rainfall. Apart from orographic features, atmospheric convection plays an important role during the monsoon and the period just preceding it.