Mode of Solar Radiation

Significant height of the sun in summertime (60-66°) and a long-lasting day (up to 17 hours) are characteristic of Altai region. Therefore, sums of direct solar radiation under the conditions of clear sky are immense. In winter time, when the height of the sun is only 13-19° and the duration of the day is only 7 hours, the inflow of radiating energy is not significant.

Cloudiness decreases the annual arrival of direct solar radiation by 35-45%. A parameter of this influence is the duration of hours of solar light (table 1).

Table I

Duration of Hours of Solar Light

Moscow	1585 hours.
Kharkov (The Ukraine)	1748 hours.
Barnaul	1936 hours.
Kosh-Agach	2634 hours.

On the flat territory the maximum quantity of solar energy is received by Kulunda and southwest areas of the Altai territory (> 100 kilocal/cm² a year or >. 418,7 joule/cm²). There is more total solar radiation in southeast of the Altai Mountains than in the Caucasus (> 130 kilo cal/cm² a year).

The magnitude of the radiating balance for the total territory of the Altai region, except mountain sites which are higher than 2500 m, remains positive for 7-8 months.

General Circulation of Atmosphere

The anticyclonic circulation prevails over the region throughout the year. Its weakening in summer occurs due to the heating of a spreading surface, while amplification at the cold period exists due to the vigorous activity of the Asian (Mongolian, Siberian) anticyclone, and often due to the frequent impacts of near to earth anticyclogenesis.

In autumn, cyclonic activity increases over south-east regions of West Siberia.

Most cyclones move from west to east, causing strengthening winds, sig­nificant fluctuations of air temperatures, rains or even snowfalls. At the end of September the Asian anticyclone begins to form in Mongolia.

During the appearance of its western spur a great decrease in temperature is observed in the region. From the beginning of November until to March the cir­culation of the cold period is established.

During winter anticyclones windless weather and precipitation usually take place. Winters are especially cold and come with increased repetitions of ultra po­lar (northeast) intrusions; as it was in 1954-55 and 1968-69. If many cyclones are observed in winter, cloudy weather with significant precipitation often ensues. There can also be an increase of air temperature > 0°C (thaws)

In spring the partial wanning of the bottom layers in troposphere above snowless areas and areas still covered with snow promotes the development of me­ridian carrying air masses. After the destruction of the crest of the Asian anticy­clone in April, the number of cyclones taking place above the region grows. This is when a warm period begins.

On the whole, the prevalence of anticyclonic processes remains unchanged in spring months (April - May) for a zone of steppes and forest-steppes in the latitudes of 48-52° North. This results in increasing air temperatures, as well as significant

reductions in precipitation and relative humidity. It also results in the formation of arid weather, and droughts often follow. Roughly 4-5 years out of 10 are arid in May - June. Significant reductions in air temperatures, late spring frosts and snow­falls are all the result of the northwest cyclone intrusions. A frequent interleaving of the relatively short periods with warm and cold weather is also observed.

In summer the thermal contrasts of various air masses moderate. However, at the beginning of summer cold snaps are still possible, often causing frosts be­cause of intrusions of the Arctic air masses behind cold fronts of northwest cy­clones. These cyclones cause strong summer snowfalls in the mountains of Altai.