User:Softlavender/W

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Rainfall distribution by month in Cairns

A wet season or rainy season is the time of year, covering one or more months, when most of the average annual rainfall in a region falls.[1] The term green season is also sometimes used as a euphemism by tourist authorities.[2] Areas with wet seasons are dispersed across portions of the tropics and subtropics.[3] While Savanna climates and areas with monsoon regimes have wet summers and dry winters, Mediterranean climates like the western United States and peninsular Italy have wet winters and dry summers. Tropical rainforests technically do not have dry or wet seasons, since their rainfall is equally distributed through the year.[4] Some areas with pronounced rainy seasons will see a break in rainfall mid-season when the intertropical convergence zone or monsoon trough move poleward of their location during the middle of the warm season.[5] When the wet season occurs during the warm season, or summer, precipitation falls mainly during the late afternoon and early evening hours. The wet season is a time when air quality improves, freshwater quality improves, and vegetation grows significantly. Soil nutrients diminish and erosion increases. Animals have adaptation and survival strategies for the wetter regime. Unfortunately, the previous dry season leads to food shortages into the wet season, as the crops have yet to mature. Developing countries have noted that their populations show seasonal weight fluctuations due to food shortages seen before the first harvest, which occurs late in the wet season.

Character of the rainfall[edit]

Wet Season storm at night in Darwin, Australia

The wet, or rainy, season covers one or more months when most of the average annual rainfall in a region falls. In areas where the heavy rainfall is associated with a wind shift, the wet season known as the monsoon.[6] Since rainfall during the wet season is predominantly due to daytime heating which leads to diurnal thunderstorm activity within a pre-existing moist airmass, rainfall is mainly focused during the late afternoon and early evening hours. This also leads to much of the total rainfall each day falling during the initial minutes of the downpour,[5] before the storms mature into their stratiform stage.[7]

The situation is different for locations within the Mediterranean climate regime. In the western United States, during the cold season from September through May, extratropical cyclones from the Pacific ocean move inland into the region due to a southward migration of the jet stream during the cold season. This shift in the jet stream brings much of the annual precipitation to the region,[8] and also brings the potential for heavy rain events.[9] The peninsula of Italy experiences very similar weather to the western United States in this regard.[10]

Effects[edit]

Monsoon in the Vindhya mountain range, central India

During the wet season, a combination of heavy rainfall and in some areas, such as Hong Kong, a wind more off the ocean, significantly improve air quality.[11] The pH level of water becomes more balanced due to the charging of local aquifers during the wet season.[12] Water also softens, as desolved materials lower in concentration during the rainy season.[13] Leaching of soils during periods of heavy rainfall depletes nutrients. Erosion is also increased during rainy periods.[5]

Life adaptations[edit]

Within the tropics and warmer areas of the subtropics, decreased salinity of near shore wetlands due to the rains causes an increase in crocodile nesting.[14] The wet season is the main period of vegetation growth within the savanna climate regime.[15] However, this also means that wet season is a time for food shortages before crops reach their full maturity.[16] This causes seasonal weight changes for people in developing countries, with a drop occurring during the wet season until the time of the first harvest, when weights rebound.[17] In tropical areas, when the monsoon arrives daytime high temperatures drop and overnight low temperatures increase.[18] Tropical species of butterflies show larger dot markings on their wings to fend off possible predators and are more active during the wet season than the dry season.[19]

References[edit]

  1. ^ Glossary of Meteorology. Rainy season. Retrieved on 2008-12-27.
  2. ^ Costa Rica Guide. When to Travel to Costa Rica. Retrieved on 2008-12-27.
  3. ^ PhysicalGeography.net. CHAPTER 9: Introduction to the Biosphere. Retrieved on 2008-12-27.
  4. ^ Blue Planet Biomes. World Climates. Retrieved on 2008-12-27.
  5. ^ a b c J . S. 0GUNT0YINB0 and F. 0. AKINTOLA. Rainstorm characteristics affecting water availability for agriculture. Retrieved on 2008-12-27.
  6. ^ "Monsoon". Britannica. Retrieved 2007-05-15. {{cite web}}: Cite has empty unknown parameter: |coauthors= (help)
  7. ^ Robert A. Houze Jr. Stratiform Precipitation in Regions of Convection: A Meteorological Paradox? Retrieved on 2008-12-27.
  8. ^ J. Horel. Normal Monthly Precipitation, Inches. Retrieved on 2008-03-19.
  9. ^ Norman W. Junker. West Coast Cold Season Heavy Rainfall Events. Retrieved on 2008-03-01.
  10. ^ BBC Weather. Country Guide: Italy. Retrieved on 2008-12-27.
  11. ^ Mei Zheng. The sources and characteristics of atmospheric particulates during the wet and dry seasons in Hong Kong. Retrieved on 2008-12-27.
  12. ^ S. I. EFE, F. E. OGBAN, M. J. HORSFALL, E. E. AKPORHONOR. Seasonal Variations of Physico-chemical Characteristics in Water Resources Quality in Western Niger Delta Region, Nigeria. Retrieved on 2008-12-27.
  13. ^ C. D. Haynes, M. G. Ridpath, M. A. J. Williams. Monsoonal Australia. Retrieved on 2008-12-27.
  14. ^ Phil Hall. Crocodiles, Their Ecology, Management, and Conservation. Retrieved on 2008-12-27.
  15. ^ Charles Darwin University. Characteristics of tropical savannas. Retrieved on 2008-12-27.
  16. ^ A. Roberto Frisancho. Human Adaptation and Accommodation. Retrieved on 2008-12-27.
  17. ^ MARTI J. VAN LIERE, ERIC-ALAIN D. ATEGBO, JAN HOORWEG, ADEL P. DEN HARTOG, AND JOSEPH G. A. J. HAUTVAST. The significance of socio-economic characteristics for adult seasonal body-weight fluctuations: a study in north-western Benin. Retrieved on 2008-12-27.
  18. ^ Official Web Site of District Sirsa, India. District Sirsa. Retrieved on [[2008-12-27].
  19. ^ PAUL M. BRAKEFIELD and TORBEN B. LARSEN. The evolutionary significance of dry and wet season forms in some tropical butterflies. Retrieved on 2008-12-27.

See also[edit]

External links[edit]

Category:Seasons Category:Climate