Ársrit Ræktunarfélags Norðurlands - 01.01.1969, Side 96

<)8
Heimild:
Einarsson, Markús Á., 1968: Um míkró- ög búveður-
fræðimælingar að Sóllandi í Fossvogi. Veðurstofa íslands,
1968.
Summary.
Daily maximum temperature at a height of 20 cm and minimum tem-
peratures at heights of 20 cm and 5 cm have been measured at Sóllandi
in Reykjavík in a horizontal, open field of grass and inside a closed
windbreak surrounding a spot of grass, which is 5x5 m2. The wind-
break is made of wood with an opening of 40 per cent.
Comparison of results from 1965—1967 shows that maximum tem-
perature is 1—2° C higher inside the windbreak in summer. At the same
time there is no definite difference in the minimum temperatures.
The minimum temperature at 5 cm is always lower than at 20 cm,
the difference being more pronounced inside the windbreak.
The 77 clear days found in the period were examined separately. In
the open field there is a risk of night frost at 20 cm in every month of
the year, although the mean value of the minimum temperature on
clear days for fuly is just above 0° C. It is shown that in all winter
months (from October to April) the lowest minimum temperatures
measured in the period have occurred in a calm and clear weather
with the ground totally covered with snow.
In 1967 the temperature at 2 meters did never drop below 0° C in
the period 21 st May to 14th October. The number of frost nights at
20 cm and 5 cm were in the same period as follows: Open field: 24
frost nights at 20 cm and 40 at 5 cm. Windbreak: 41 frost nights at 20
cm, 57 at 5 cm. In 1965 and 1966 night frost was not so frequent, but
corresponding figures are presented.