East Asian rainy season

In China, the term "plum rain" (梅雨; meiyu) refers to the rainfall during the fourth and fifth lunar months. It originates from the traditional belief that when plums ripen and begin to fall in the regions south of the Yangtze River during this period, moisture evaporating from the plants transforms into rain. ==Formation==

An east–west zone of disturbed weather during spring along this front stretches from the east China coast, initially across Taiwan and Okinawa, later, when it has shifted to the north, eastward into the southern peninsula of South Korea and Japan. In Taiwan and Okinawa, the rainy season usually lasts from May to June. In Russian Primorsky Krai, Japan, and Korea, it lasts from June to July (approximately 50 days). In eastern China (especially the Yangtze and Huai River regions), it lasts from mid June to early July. The weather front forms when the moist air over the Pacific meets the cooler continental air mass. The front and the formation of frontal depressions along it brings precipitation to Primorsky Krai, Japan, Korea, eastern China, and Taiwan. As the front moves back and forth depending on the strength of cool and warm air masses, there is often prolonged precipitation and sometimes flooding in eastern China. However, in the years that it does not rain as much as usual, a drought might result. The rainy season ends when the warm air mass associated with the subtropical ridge is strong enough to push the front north and away. ==Effects==

The high humidity in the air during this season encourages the formation of mold and rot not only on food but on fabrics as well. Environmentally, heavy rains encourage mudslides and flooding in all areas affected. The most rain in a one-hour period as recorded in Japan was in Nagasaki in 1982 with . The highest overall recorded rainfall during the rainy season in Japan was in 2003 when Miyazaki Prefecture recorded rains of . Japan In Japan, the rainy season is called , and lasts from early June to mid-July in most of the country (Honshu, Kyushu and Shikoku), approximately June 7 to July 20 in the Kansai and Kantō regions in Honshū. The season is roughly a month earlier (early May through mid-June) in Okinawa (the southernmost region of the country). There is no pronounced season in Hokkaidō (the northernmost region of the country) because the front usually attenuates before it reaches the region so that it cannot produce the abundant rainfall. is also known as . The pop artist Eiichi Ohtaki produced a popular song by this name, and a Second World War Japanese naval ship was also given this name. Korea The rainy season is between June and mid-July. It is caused by hot and humid high pressure forming in the Sea of Okhotsk due to the North Pacific anticyclone combining with Asiatic continental high pressure. When the two meteorological events meet they form a long (, from and ). Beginning in late May, the North Pacific high pressure forces the weaker continental anticyclone south of Okinawa Island. This fall to the south then reverses and gradually strengthens as it moves northwards back towards the Korean peninsula. On landfall, heavy monsoon rains lead to torrential downpours and flooding. By August the system has weakened as the southern systems retreat towards the Philippine archipelago. By early autumn, the North Pacific high-pressure system is pushed away as Asiatic continental cold high pressure moves southwards. This produces inclement weather although not on the scale of the summer monsoons. Korea can, however, be struck by typhoons during this period. == Timing ==

In some years, the rainy season's actual beginning and end are under debate. For example, in 2005, the subtropical ridge moved quickly northward in late June/early July. The weather front skipped the Yangtze region and there was no rainy season there. Then, the ridge retreated southward and there was significant rainfall in the region. This gave rise to the question of whether this was the summer-type rainfall pattern that is common after the first rainy season or the second rainy season. Some meteorologists even argued that the rainy period in late June was not a true rainy season. == See also ==