a 
ON TEMPERATURE OBSERVATIONS IN LOCH EARN. 635 
NuMBER oF Hours’ SUNSHINE. 
August 3 3? hours August 16 : 6 hours 
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. 6 24, amet ; : On 
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LO Ti 28 ‘ ; Sk As 
Discussion of the observations will best centre round typical diagrams. Fig. 6 
consists of the temperature-depth curves drawn from the observations at alternate hours at 
the five stations, from noon on 5th August to noon on 6th August.* Reference to fig. 15 
will show that at noon on the 5th the wind changed from east to west, and we find that 
at that time there is the temperature distribution associated with an east wind, z.e., a 
much sharper temperature discontinuity at the west end than at the east. With the 
change of wind the distribution gradually changes to a west wind type, with a sharp 
discontinuity at the east end. It is very interesting to compare the curves for Stations 
I. and V., and to see how the types gradually change. ‘I'he type at 12 noon on the 
5th at Station I. is practically the same as that at Station V. on the 6th, while the 
type at Station V. at noon on the 5th is practically the same as at Station I. at noon 
on the 6th. The curves for Station II. are similar to those at Station I., and those 
at Station [V. follow the Station V. curves, while at Station III. the type does not 
change much. 
Vig. 7 * shows a reversal of this on 10th and 11th August, as the wind changed from 
west to east about 9 p.m. on the 10th. Ina similar manner fig. 8 * (7th August) shows 
the type of curves to be found with a steady west wind of no great strength, the 
principal points to be noted being the sharper discontinuity and higher surface 
temperature at the lee end of the loch, z.e. the east end. The effect of the direction of 
the wind in determining the temperature distribution in a lake must be clearly kept in 
view before it is possible to understand the nature of the variations which are observed. 
The object of these diagrams is to show this effect and to illustrate: how rapidly the 
effect of a change in the direction of the wind makes itself felt. 
Fig. 9 * shows the result of observations at Station III., from 12th to 23rd August, 
and during the whole of this period there was an absence of strong winds and a great 
deal of sunshine. The raising of the surface temperature and the slackening of the 
discontinuity in temperature will be observed. Had the winds been strong, there 
* See explanation of diagrams, p. 652. 
