Abstract

     The presence of large lakes has a marked influence on micro and mesoclimate, though this problem has been given relatively little attention in the literature.   Collectively, the study of this influence of lakes on climate may be called "limnoclimatology", and the effects themselves called "lake effects".   These lake effects are mainly due to the following physical properties of water: thermal capacity, thermal conductivity, density differences with temperature variation, and the optical properties of transparency and reflectivity.   Together these properties control the heating and cooling rates of lakes, resulting in temperature contrasts between lake and land - the lakes being cooler in summer, and warmer in winter than the mainland.   Other major factors involved in the formation, regulation, and influence of limnoclimates include the following: volume; depth; surface area; and shape of lakes, directional orientation and presence of islands and other landforms in lakes, altitude and latitude, formation; duration; and extent of ice cover in winter, surrounding vegetation patterns; topography; and relief, and distance from oceans and seas.   Localized influences include shoreline morphology and vegetation types, the location and size of cities, and forest and agriculture patterns.   The main control on climate surrounding large lakes, however, is the macroclimate, and all lake effects are simply various modifications of this.   Major climatic parameters influenced by lakes include temperature (which is the driving force for most other limnoclimatic phenomena), precipitation, atmospheric moisture, wind, and various mesoscale severe weather events.   Lake effects strongly influence many natural and human processes in their vicinity, including vegetation type and pattern, suitability for various agricultural products, population distribution, tourism, transportation, and numerous others, and thus are of major geographic significance where they occur.