Weather and Сlimate

Climatology is concerned with the prevailing state of the atmosphere, including average climatic values, the frequency of values within stated ranges, weather types and their characteristics, and the explanation and distribution of both climatic elements and general climatic types. Of particular geographic interest are the interrelationships of climatic elements and types with other physical and biologic features and with human activity.

The conditions of the atmosphere which determine an area's weather or climate are temperature, precipitation (rain and snow), atmospheric pressure, winds, humidity and percentage of cloudiness and sunshine. The average of these conditions over a period of many years make up an area's climate. Tropical climate reigns over 36.2 per cent of the earth’s surface, moderate – over 37.2 per cent, cold – over 18.8 per cent, dry – over 10.5 per cent, snow-bound climate – 7.3 per cent.

Because the combination of climatic conditions differs from place to place, geography is concerned with the classification of areas according to climate. Forests are commonly found where the climate is humid and not too cold for trees to grow. Grasslands generally develop in subhumid or semiarid regions where the rainfall is less than that necessary for trees. Deserts occur in places where there is so little rainfall that even grass has difficulty for growing. Tundras are found where the climate is cool to cold throughout the year.