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 APPROVED FOR RELEASE: 2009/06/16: CIA-RDP01-00707R000200070024-2

Icelandic low and the equally intense Siberian high direct a flow of cold, moist Atlantic air from the west or southwest over Poland. Imbedded in this flow is a moderate incidence of cyclonic activity. These storms and their associated fronts cause long periods of inclement weather, characterized by overcast skies, frequent precipitation, poor visibility, and a raw, damp condition. This regime is interrupted occasionally when invasions of polar continental air from the Siberian high bring very cold, dry, sunny weather for brief periods. During summer (June through August) the extension of the Azores high over Europe directs a flow of warm, less moist Atlantic air from the west or northwest over Poland. Although showers and thunderstorms are frequent, the weather is very much improved in this season, with mainly partly cloudy skies, better afternoon visibility, lower relative humidity, and a generally mild pleasant condition. On occasions during summer, hot dry winds from the south or southwest cause abnormally high temperatures. Spring (March through May) and autumn (September through November) are transitional seasons.

Winter temperatures are quite low. Mean daily maximum temperatures generally rise only to freezing or slightly above (Figure 2), whereas mean daily minimums are in the 20's (°F.) and teens. The lowest temperatures, resulting from outbreaks of cold air from the east, often fall below zero and occasionally reach -20°F. and -30°F. Maximum cloudiness occurs in winter, averaging over 70% throughout the season. Low-hanging stratocumulus cloud decks are widespread, and there are only occasional breaks in the overcast. Winter precipitation is frequent and mostly in the form of snow. However, accumulations are small, and mean monthly amounts are generally less than 2 inches over most of the country. The winter snows and low temperatures result in a snow cover that is persistent in the south but becomes intermittent in the north. The poorest visibility conditions are encountered during this season. Fogs are common in the morning and occasionally last throughout the day. The frequent overcast skies and restricted visibilities result in long periods of dull, gloomy weather. Relative humidity remains high throughout winter, in the 80's (%) and 90's, and creates a penetrating dampness which is alleviated only during the invasions of drier air from the east. Surface winds are light to moderate and predominantly southwesterly in this season over most of the country. Strong winds, 30 knots are greater, range from occasional to frequent in the southern mountains.

Summer temperatures are pleasantly mild or warm. Mean daily temperatures range between maximums in the upper 60's (°F.) or low 70's to minimums in the low or middle 50's. Mean temperatures are 10 to 20 degrees cooler in the southern mountains. During the infrequent spells of hot, dry winds from the south or southeast, temperatures rise abruptly to the 90°F. to 100°F. range. Mean monthly cloudiness is at a minimum in this season, generally averaging between 55% and 60% throughout the country. Cloud cover is greatest during the afternoon, when convective activity expands the cumulus puffs into large cloud masses. The frequency of precipitation remains high in summer. The showery type of rainfall results in increased mean monthly amounts, generally ranging between 2 and 6 inches. The heaviest rain falls during thunderstorms, most of which occur in May through August on 3 to 7 days per month. Light fogs in the early morning also remain fairly frequent but quickly dissipate by late morning. Afternoon visibility in this season is much improved and offers the best conditions of the year. Relative humidity is more tolerable in summer, especially when afternoon average values are mostly in the 55% to 65% range. Weak westerly winds prevail, but strong winds of short duration may occur during thunderstorms.

D. Military geographic regions (C)

Poland is divided into three military geographic regions on the basis of environmental conditions that would affect operations: the Polish Plains, the Sudeten Mountains and Hills, and the Carpathian Mountains and Hills (Figure 25). The principal geographic factors that make each region distinct are shown in Figure 3.

1. Polish Plains

This region, which covers approximately 90% of Poland, is suited for most military ground operations. It is predominantly a cultivated, gently rolling plain (Figure 4); there are mixed forests on sandy soils in lowlands, scattered marshes, and swamps along the middle and lower reaches of streams. A few scattered areas of low, forested hills and stream-dissected uplands rise above the surrounding plain in the southeast. The region is drained principally by the extensive Oder and Vistula systems, which are characterized by wide, meandering rivers having marshy flood plains. The road and rail networks are well-developed and serve both the numerous large cities and populous rural areas; the networks are extensive and especially dense west of the Vistula.

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APPROVED FOR RELEASE: 2009/06/16: CIA-RDP01-00707R000200070024-2