Climate

The climate of Moscow is continental, modified by the temperate influence of westerly winds of Atlantic origin. Precipitation is moderate, 23 inches (581 millimetres) a year, with a marked summer maximum that reaches a peak in July. A considerable part of the precipitation falls as snow; beginning usually about mid-October—though permanent snow cover is not normally established before the beginning of November—it lasts generally until mid-April. Winters are thus long and dark, although southerly airstreams occasionally bring days with temperatures above freezing. Conversely, northerly winds from the Arctic bring very sharp drops in temperature, often accompanied by clear, brisk weather with low relative humidity. December, January, and February are the driest months. Thus, although the January average temperature is 14 °F (−10 °C), there can be considerable variation; the minimum recorded temperature is −44 °F (−42 °C). Moscow employs a large number of workers and a fleet of mechanical devices to keep the streets clear of snow. Spring is relatively brief, and the temperature rises rapidly during late April. Summers are warm, and July, the warmest month, has an average temperature of 65 °F (18 °C); a maximum temperature of 99 °F (37 °C), however, has been recorded in August. Rainy days are not uncommon, but the summer rainfall often comes in brief, heavy downpours and thunderstorms. Autumn, like spring, is short, with rapidly falling temperatures.

Human activity has modified the climatic conditions as well as the relief and hydrology. The vast number of buildings creates the so-called urban heat-island effect, causing the average annual temperature in the central city to be up to 3 °F (2 °C) higher than the temperature in open country outside the city. Plants in central parks and gardens blossom a week or more earlier than those in the outer suburbs. The temperature differential is most marked on clear winter nights, when the buildings radiate heat; it can be as much as 18 °F (10 °C) or more. The city centre also receives heavier rainfall than the surrounding countryside and averages about 100 hours less sunshine per year.

Until the late 1950s there was increasing air pollution in Moscow. Smog was common, often with heavy concentrations of sulfur dioxide. A major campaign to control noxious emissions was launched, assisted greatly by a changeover from coal to natural gas as the principal fuel. Some seriously polluting factories were moved out of the city. The resulting improvement in Moscow's air has been marked, although the growing number of motor vehicles—still far fewer than in cities of comparable size—has increased the concentrations of such exhaust pollutants as carbon monoxide in certain parts of Moscow.

Layout and architecture

A map of Moscow presents a pattern of concentric rings that circle the rough triangle of the Kremlin and its rectangular extension, the Kitay-gorod, with outwardly radiating spokes connecting the rings, the whole pattern being broken by the twisting, northwest–southeast-trending Moskva River. These rings and radials mark the historical stages of the city's growth: successive epochs of development are traced by the Boulevard Ring and the Garden Ring (both following the line of former fortifications), the Moscow Little Ring Railway (built in part along the line of the former Kamer-Kollezhsky customs barrier), and the Moscow Ring Road.