PrimoryeGeography
AIR CIRCULATION

 
    The monsoon climate characteristic of the entire Russian Far East is particularly pronounced in Primorye. Solar rays heat the surface of both land and ocean, which then cool non-uniformly. In winter, the land cools rapidly. At that time of the year, cold, dense and heavy air masses are generated in the center of the Asian continent (over Northern Mongolia and southern Eastern Siberia) to form an area of high atmospheric pressure, the Siberian anticyclone. Japan Sea  At that very time, water cools slower to lead to formation over the northwestern Pacific an area of declined atmospheric pressure, the Aleutian minimum. Because of pressure difference, overcooled, dense, dry air from Siberia flows to the warmer ocean coastline. In this case, it fills the area over Primorye to rush to the reduced pressure area over the Pacific. 
    Cold, but dry and sunny weather sets in over Primorye. The prevalent winds in that period are westerly and northwesterly. These air masses form a continental monsoon in winter to reach especially significant force on the coast.
 In summer, the land warms up quicker, and warm air forms over it and the continent to form a low-pressure area. At that time, the Pacific is colder than the land, and the pressure over it higher; this is where the area of high air pressure forms. The moist and less warm air from the ocean and seas rushes to the continent. This is how the Pacific summer monsoon with southerly and southeasterly winds forms in Primorye.
     In the first half of summer, due to the fact that air masses are carried out from the Yellow, Japan and Okhotsk seas, the summer monsoon is concomitant with drizzles. It does not possess a large reserve of moisture to leave it chiefly on the coastal ridges and hills. That is why in late spring and early summer (May and June) we often have foggy rainy weather in Vladivostok, but again in Ussuriisk 100 km to the north, and moreover in Grodekovo and Spassk, there are many more clear days at this time of the year.
    In the second half of summer and early fall, the monsoon embraces the entire territory of Primorye to carry large amounts of moisture. This is the time of intensive and protracted torrential rains, not infrequently accompanied by powerful cyclones coming from tropical areas, typhoons.
    The continental winter monsoon noticeably prevails over the sea monsoon: northwesterly and northerly winds prevail in Vladivostok from September to March, and in Partizansk even from September to April. Precisely for that reason, the number of sunny days is so great. Again, that is why Primorye has such unusually cold weather for such low latitudes in winter. The mean temperature in Vladivostok in January is minus 14.4oC, while in Sochi, situated on the Black Sea coast on about the same latitude, the mean air temperature in January is plus 6.1oC.
    Depending on the direction in which ridges and river valleys extend, and on the nature of sea coasts in some Primorye sites, the winds in near-ground layers may change their basic directions. Relief specifics and the direction of the coastline lead to forming in Primorye of local winds, breezes, foehns, and hot dry winds.
    Breezes are observed in protected inlets of Japan Sea coastline, in narrow coastal strips. Mountains prevent breezes from spreading inside the continent. In summertime, a daytime breeze would normally start at 10-11 A.M. to continue till sunset. It would blow from the sea to the heated coast. A nighttime breeze from cooled cost to the sea would last 6-7 hours. During the cold period of the year, due to strong cooling of land at nighttime, the diurnal breeze would be less protracted.
    Sometimes in winter relatively warm dry winds, foehns, arise in coastal areas. They form when air streams flow over mountain ridges. In settling, the air heats to become drier. In this case, the temperature of ground air layers rises and winter direction changes. In spring, foehns hasten snow melting.
    Hot dry winds УvisitФ the western districts of Primorye, penetrating from Northeast China and Mongolia. The most intense, often recurrent hot dry winds are characteristic of the Khanka Plain in April and May.




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