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The purpose of the present paper is to review the application of numerical weather prediction techniques in the daily operational routine of the Hydrometeorological Service of the USSR. The theoretical aspects of numerical weather prediction models used have been discussed by the authors in original papers and will not, therefore, be repeated here.

Small water bodies create their own characteristic local meteorological environments. The heat and water budgets will generally vary with surface area and water depth. If a small pond gradually becomes covered by vegetation, its meteorological conditions will change. On occasion, a vegetated area may change into a pond, complete with vegetation established in the water and extending above the surface. Such are beaver ponds and other flooded areas. The paper discusses the main features of the development of beaver ponds and their heat and water budgets at different stages. The energy budget programme used was previously developed by the authors, but it has been modified to account for the different phases of the pond development. The effects of the various physical changes are evaluated by comparing the individual heat and water budget terms for different stages between an open lake surface and a forest cover. The local heat budget will only be affected on a small scale by the establishment of a b...

Canadian definitions of break‐up and freeze‐up are shown to have changed substantially on several occasions since 1957. This paper demonstrates that because of these changes, great care must be exe...

The rate of heat loss from the human body by low temperatures and wind is commonly referred to as “Wind Chill”. Traditionally the term means the rate of heat removal from the bare skin only. It neglects such important factors as clothing insulation, metabolic heat generation and sunshine. This paper presents a new windchill index which includes the above parameters and discusses its advantages over the present concept of windchill. The principal advantage being that the new index may be directly correlated to human comfort or discomfort. In addition, the windchill may be adjusted for different clothing levels, metabolic rates, and solar radiation.

REVIEW PAPER PRESENTED OCTOBER 5, 1967 AT THE XIVTH IUGG GENERAL ASSEMBLY LUCERNE, SWITZERLAND

This paper describes the preparation of a preliminary set of maps of gradient‐level wind climate over Canada and some neighbouring regions of the United States. The data for this study were drawn from twice‐daily records of radiosonde ascents at a network of ten Canadian upper air stations. The period covered by the data was 1960–69, and this was supplemented by statistical information on upper level winds at fourteen points in the United States. The analysis and subsequent mapping were carried out for 300 and 500 m above ground level and were based on a number of statistical models: the bivariate Gaussian distribution of wind velocities characterized by the vector mean and standard vector deviation, monthly Weibull distributions of wind speed and a new model of extreme annual wind occurrences developed from a consideration of wind as a stochastic process.