BULLETIN OF IMSP - (IMD), Pune

Cherrapunji & Mawsynram: Wettest Places on the EarthD. S. Pai and Pulak GuhathakurtaIndia Meteorological Department, Shivajinagar, Pune.Cherrapunji (elevation 1313m) is a station situated at the southern slopes of theKhasi Hills of Meghalaya, (Meghalaya means ‘abode of clouds’) in northeast India.Mawsynram (elevation 1401m) another station in Meghalaya is situated only 16kilometers west of Cherrapunji. Blessed by the rain Gods, both these places, Cherrapunji& Mawsynram, receive abundant rain throughout the year except during the wintermonths. In these areas, the main mechanism of rainfall areas is the direct orographiclifting of air. However, heavy rains also occur in association with the cyclonic storms.During the pre and post monsoon periods, these areas experience short, sharp convectiveshowers. On the other hand the summer monsoon rainfall is mostly orographic.The rainfall observation at Cherrapunji was started in late 19 th century itself.However, the automatic rainfall monitoring was introduced in the early 1970s. AtMawsynram, the rainfall observations were started only in the beginning of the 1940s.Thapliyal and Kulshrestha (1992a) found that the annual mean rainfall for Mawsynram(1941-1978) is 11,873 mm, while it is 11,314 mm for Cherrapunji (1852-1987). Fromtheir analysis it was concluded Mawsynram in the Meghalaya as the rainiest place in theworld (on the basis of annual rainfall) ahead of Cherrapunji and another station Waialeale(elevation 1548 m and mean annual rainfall 11,438 mm (1911-73)), in Hawaii, USA.However, it is to be noted that the data period used for Mausynram was 38 years ascompared to 63 years for Waialeale and 138 years for Cherrapunji. We computed meanannual rainfall of Mawsynram and Cherrapunji using data for a common period of 1940-2005, during which data were available from both the stations. As per this computation,the annual mean rainfall of Mawsynram and Cherrapunji is 11510.9 mm and 11150.4mmrespectively. Thus Mawsynram can rightly be called as the wettest place of world.But for the annual mean rainfall, the Cherrapunji has a series of world records in itscredit for observed rainfalls pertaining to different time durations. Some of the significantrainfall values, which were collected from the data archive of India MeteorologicalDepartment, Beresford & O’Hare, 1998 and Blandford (1886-1888) are listed below.Time Duration Rainfall Date1 hour 420 mm 16 th June 19951 day 1563 mm 16 th June 19952 day 24930 mm 15-16 June 19954 days 3721 mm 12-15 September 19741 month 9300 mm July 18612 months 12767 mm June-July 18613 months 16369 mm May-July 18616 months 22461 mm April-September 186115