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June Gloom is a southern California term for a weather pattern that results in cloudy, overcast skies with cool temperatures during the late spring and early summer, most commonly in the month of June. Low-altitude stratus clouds are formed over the ocean, then transported over the coastal regions by the wind. The overcast skies often are accompanied by fog and drizzle, though usually not rain. June Gloom in southern California is caused by the marine layer effect common to the West Coast, and is enhanced by the Catalina eddy local to southern California. May and June together are usually the cloudiest months in coastal Southern California. June Gloom has other colloquial names if the same weather pattern occurs in May, July, or August. June Gloom is stronger in years associated with a La Niña, and weaker or nonexistent in years with an El Niño. This weather pattern occurs in other parts of the world where climates and conditions are similar. Scientists study the cloud fields that make up June Gloom to increase understanding of cloud behavior at the onset of precipitation. ==Phenomenon== A typical June Gloom morning consists of marine stratus clouds covering the coast of southern California,〔 extending a varying distance inland depending on the strength of the June Gloom effect that day. The clouds, which are formed by the marine layer, move in at night, usually after midnight, and typically dissipate in the late morning, giving way to clear, sunny skies. During a heavy June Gloom season, the condition may persist into the afternoon, or even all day during an exceptionally strong event. Often, the air is saturated with moisture, and fog also develops, along with frequent light mist and occasional drizzle. Fog and drizzle normally are found near the furthest inland extent of the gloom, where the cloud deck is closest to the ground.〔 By late morning to early afternoon, solar heating usually is sufficient to evaporate the clouds, and the sun emerges. The phenomenon forms earliest and lasts longest at the coast, with weaker effects as it moves further inland. When the marine layer is strong and deep, clouds can fill the Los Angeles Basin and spill over into the San Fernando Valley and San Gabriel Valley, even extending into the Santa Clarita Valley on exceptionally strong June Gloom mornings. If the condition is not as strong, the Basin may be filled while the valleys may be clear. It is not uncommon for motorists to drive over the Sepulveda Pass from the clear, sunny San Fernando Valley and plunge into a cloudy, fog-filled Los Angeles. On a weak June Gloom morning, the clouds and fog may only be present within a mile or two of the coastline, affecting only the beach cities. The months of May and June are typically the cloudiest months of the year in coastal southern California, having only 59% and 58% sunny days, respectively, on average.〔〔(San Diego Union Tribune, June 8, 2004 )〕 The number of days in May and June that are "gloomy" vary from year to year. Anomalies in sea surface temperature can be used to forecast the number and intensity of June Gloom days.〔 Years with warmer ocean temperatures, referred to as El Niño, may result in fewer gray days in May and June.〔(San Diego Union Tribune, May 7, 2010 )〕 Cooler ocean temperatures, associated with La Niña, usually foretell a more gray period. The climate chart below shows a clear drop in the ''mean monthly sunshine hours'' and ''percent possible sunshine'' for the months of May and June, which are the two months when the June Gloom pattern is the strongest. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「June Gloom」の詳細全文を読む スポンサード リンク
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