. Ecological animal geography; an authorized, rewritten edition based on Tiergeographie auf ockologischer grundlage. Zoogeography -- Geographical distribution; Animal ecology. COMMUNITIES IN STANDING WATERS 323 continues up to the maximum of temperature. This results in convec- tion currents until a uniform temperature of 4° has again been reached. The water is now in unstable equilibrium and wave action usually produces a complete mixing of the waters of the lake, making what is called the spring overturn. Thereupon the heating of the surface water goes on from the end of April or the beginni
. Ecological animal geography; an authorized, rewritten edition based on Tiergeographie auf ockologischer grundlage. Zoogeography -- Geographical distribution; Animal ecology. COMMUNITIES IN STANDING WATERS 323 continues up to the maximum of temperature. This results in convec- tion currents until a uniform temperature of 4° has again been reached. The water is now in unstable equilibrium and wave action usually produces a complete mixing of the waters of the lake, making what is called the spring overturn. Thereupon the heating of the surface water goes on from the end of April or the beginning of May (summer stagnation) until a renewed cooling again brings about equilibrium and the autumn overturn. Water which has a temperature of 4° thus Winter Spring Summer Autumn Winter Spring Summer Xll I II III IV V VI VII VIII IX X XI XII I II III IV V VI VII VIII. Warming Cooling Warming Fio. 92.—Schematic representation of the temperature conditions in a body of water in the temperate zone during the course of the year. The isotherms are continuous lines when the stratification is direct, dotted when it is inverse. Spring overturn at A-B and E-F, autumn overturn at C-D, summer stagnation at B-C and F-G. always fills the lower levels of the deeper basins; but twice a year it rises to the surface, in spring and fall. Between these two points the 4° isotherm describes a curve which sinks lower in the summer than in the winter and above which the water is arranged in direct stratification in summer and in inverse stratification in the winter (Fig. 92). The change from day to night also sets up convection currents. Warming during the day in summer is followed by a cooling at night, which causes a sinking of the upper strata down to a stratum of like temperature. As a result of this an equalization of temperature among these strata occurs, so that these upper strata differ but little in. Please note that these images are extracted from scanned page images that may have been
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Keywords: ., bookcentury1900, bookcollectionbiodive, booksubjectanimalecology
