Fix the mistake: Japan's Weather

Air Masses Near Japan and the Four Seasons

Japan's four seasons are brought about by the changing dominance of the surrounding air masses. By learning the characteristics of each air mass, we can understand the weather of each season.

Basic Knowledge

Main air masses around Japan:
① Siberian air mass: Northern Eurasian continent; cold and dry. Develops in winter.
② Okhotsk Sea air mass: Okhotsk Sea; cold and humid. Develops during the rainy season and autumn rains.
③ Ogasawara air mass (Pacific high): Pacific Ocean; warm and humid. Develops in summer.
④ Yangtze River (Chang Jiang) air mass: Chinese continent; warm and dry. Brings migratory high-pressure systems in spring and autumn.
Weather of the four seasons:
Spring and autumn → migratory high-pressure systems from the Yangtze River air mass and low-pressure systems pass alternately (alternating cold and warm periods). Rainy season → The rainy-season front remains stationary as the Okhotsk Sea and Ogasawara air masses compete. Summer → The Ogasawara air mass dominates, bringing southeasterly seasonal winds and hot, humid weather. Winter → The Siberian air mass dominates, bringing a west-high, east-low pressure pattern and northwesterly seasonal winds.

Further Study (Background and Significance)

Even within Japan, the climates of Hokkaido, Tohoku, Kanto, Kinki, Kyushu, and Okinawa differ greatly. As climate regions, Japan can be divided into Hokkaido (subarctic), the Sea of Japan side (heavy snowfall), the Pacific side (dry winters), inland areas (large temperature differences), the Seto Inland Sea region (warm and dry), and the Nansei Islands (subtropical).
The early-spring first spring storm is a strong southerly wind that blows between the beginning of spring and the spring equinox; a southerly wind accompanying the passage of a low-pressure system is a typical example. The autumn first winter wind is the first strong northerly wind from mid-October to the end of November, signaling the transition to a winter pressure pattern.
By remembering the connections between air-mass names and seasons, we can quickly tell from a weather map which air mass is currently dominant.

Points of Caution (Easily Confused)

① Remember the combinations of temperature and humidity of the four air masses (Siberian = cold and dry, Okhotsk = cold and humid, Ogasawara = warm and humid, Yangtze River = warm and dry). ② West-high, east-low (winter) and south-high, north-low (summer). ③ Migratory high-pressure systems occur in spring and autumn. ④ Cool summers occur when the Okhotsk Sea air mass is unusually strong.

Practice

1. Name the air mass that strongly affects Japan in winter.
2. Express the winter pressure pattern using four kanji characters.
3. In which seasons do migratory high-pressure systems often appear?