Definition of monsoon

The normal date for monsoon onset over Kerala is June 1, determined by IMD based on monsoon onset data during 1961-2019. But historically monsoon onset dates have had very large variation also, with some arrivals as early as mid-May and some as delayed as past mid-June. PREMIUM Forecasting monsoon onset is one of the most challenging aspects of IMD’s work.(AFP) Overall, the most delayed monsoon onset was on June 19, 1972, and the earliest on May 18 in 1990, IMD officials said. Among the 16 El Nino years since 1950 for instance, the earliest monsoon onset took place on May 18 in 2004 while the most delayed was on June 19 in 1972, according to data with India Meteorological Department (IMD). Monsoon onset date is typically forecast by the IMD around mid-May, and helps the farming community determine their sowing cycles for the Kharif crop. But forecasting monsoon onset is one of the most challenging aspects of IMD’s work. The challenge is being felt this year too. A June 4 predictionOn May 16, the IMD predicted that the monsoon was likely to make onset over Kerala on June 4 with a model error of +/-4 days. On June 4, the department issued a statement: “Conditions are becoming favourable with an increase in westerly winds over south Arabian Sea. Also, the depth of westerly winds is gradually increasing and today, the 04th June, the depth of westerlies has reached up to 2.1 km above mean sea level. The cloud mass over Southeast Arabian Sea is also increasing. We expect that th...

A monsoon is a seasonal reversal in wind patterns over a region. The word “monsoon” comes from the Arabic word mausim, meaning “season.” The seasonal wind shift is usually accompanied by a dramatic change in precipitation. The best known example of a monsoon occurs over the Indian subcontinent. In summer, the sun warms the land and the air above it. With cooler air lying over the oceans that surround the subcontinent, a horizontal pressure gradient is established that generates winds directed from the ocean to land. The air flowing over the water remains over the ocean a long time, which causes it to gain moisture. This wind brings humid air inland. The solar heating over land triggers convection that produces rain. Orographic lifting of air by the Himalaya Mountains generates more rain. The summer monsoon is a wet season over land. These rains can cause major flooding, but they are vital to agriculture and the economy. During the winter season, the air above the land cools faster than the air over the water, establishing a pressure gradient force from land to sea. The winds are therefore reversed from the summer monsoon flow — from land to sea instead of from sea to land. Sinking air above the land suppresses cloud development and precipitation. The winter monsoon is a dry season. Other parts of the world also have monsoons. The North American monsoon, also called the Arizona monsoon, occurs over the southwestern United States and northwestern Mexico. It results in a rain...

Recent Examples on the Web Jones’s, unfortunately, coincided with an unseasonable monsoon that made all of the outdoor spaces unusable, driving away every smoker. — Jada Yuan, Washington Post, 6 June 2023 This is an abrupt change from the past two years of wet monsoons that brought record-breaking rain to the state. — Ellie Willard, The Arizona Republic, 6 June 2023 Weather San Diego County might get July weather next week due to early start of summer monsoon May 9, 2023 Also starting soon, is the annual season for blue whales migrating along the coast of San Diego. — The San Diego Union-tribune Staff, San Diego Union-Tribune, 10 May 2023 And, for example, if the overturning current in the Atlantic Ocean weakens, or even collapses, the consequences could be dire – including very cold winters in Western Europe, rapid sea level rise and disruption to tropical monsoons. — Laura Paddison, CNN, 5 May 2023 By late August, afternoon storm clouds often formed over the mountains, bringing monsoons that seeped through the roof and flooded their land. — Patrick Lohmann, ProPublica, 24 Apr. 2023 India’s weather office on Tuesday forecast a normal monsoon this year, which could lift demand for scooters, Aggarwal said. — Ragini Saxena, Bloomberg.com, 13 Apr. 2023 They were used to store water collected during monsoon season for drinking, washing, irrigating crops and cooking during the arid balance of the year. — Chris Klimek, Smithsonian Magazine, 13 Apr. 2023 The peril isn’t that far-...

The North American monsoon is a complex weather process that brings moisture from the In the monsoon area, the late spring period is very hot and dry, because the dry western side subtropical high pressure ridge and dry continental air have not begun to 'shift' northwards yet. During this period, inland areas have extremely low relative humidity, and characteristically very low [ citation needed] In early summer, the monsoon starts with a shift in wind patterns as Mexico and the southwest U.S. warm under intense solar heating. The thermal low sets up circulation that brings pulses of low level moisture from the As precipitable water values rise in early summer, brief but often torrential thunderstorms can occur, especially over mountainous terrain. Effects [ ] Monsoon precipitation accounts for a substantial portion of annual precipitation in northwest Mexico and the Southwest U.S. Most of these areas receive over half their annual precipitation from the monsoon. Monsoons often play a role in reducing Once the monsoon is underway, mountain ranges, including the Sierra Madre Occidental and the Rainfall during the monsoon is not continuous. It varies considerably, depending on a variety of factors. There are usually distinct "burst" periods of heavy rain during the monsoon, and "break" periods with little or no rain. The monsoon ridge is almost as strong as the one which develops over Asia during the summer. However, since the lower level moisture flow is not as persistent a...

Kalnay , E. , R. Balgovind , W. Chao , D. Edelmann , J. Pfaendtner , L. Takacs , and K. Takano , 1983 : Documentation of the GLAS fourth-order general circulation model. Vol. 1: Model description. NASA Tech. Memo 86064 [Available from the library of NASA Goddard Space Flight Center, Greenbelt, MD 20771.] . Kalnay , E. , R. Balgovind , W. Chao , D. Edelmann , J. Pfaendtner , L. Takacs , and K. Takano , 1983 : Documentation of the GLAS fourth-order general circulation model. Vol. 1: Model description. NASA Tech. Memo 86064 [Available from the library of NASA Goddard Space Flight Center, Greenbelt, MD 20771.] .)| false• Search Google Scholar • Export Citation • Takacs , L. L. , A. Molod , and T. Wang , 1994 : Documentation of the Goddard Earth Observing System (GEOS) general circulation model Version 1. NASA Tech. Memo 104606, 100 pp. [Available from the library of NASA Goddard Space Flight Center, Greenbelt, MD 20771.] .)| false• Search Google Scholar • Export Citation • Abstract The monsoon is interpreted as an intertropical convergence zone (ITCZ) substantially away (more than 10°) from the equator and the existence of the ITCZ does not have to rely on land–sea contrast. Land–sea contrast can provide a favorable longitudinal location for the ITCZ but this role can be replaced by sea surface temperature contrast in the longitudinal direction. Thus, the interpretation of the monsoon presented herein differs from the long-held fundamental belief that its basic cause is land–s...