By the climate of a
district is meant its average weather. This is largely determined by
its temperature and its rainfall, and very much depends on its
altitude and its distance from, or proximity to, the sea. No British
county is large enough to have a distinctive climate of its own:
each shares in that of the geographical region to which it belongs.
The following table,
compiled from the late Dr Buchan’s papers, shows the mean
temperature over forty years ending 1895 of several stations in
Forfarshire; and, when allowance has been made for local conditions,
it illustrates how uniformly temperature varies with altitude.
The monthly details
contained in the same papers prove that in Forfarshire July (570 F.)
is the warmest, and January (37° F.) the coldest month, while the
mean annual temperature is 46° F. They indicate also the marked
differences of temperature at various periods of the year ; for
example, after the equinoxes, or between May and June. Dundee is
here chosen—it is typical of the others—and the monthly mean over
the same forty years is given in degrees Fahrenheit.
The cultivation of a
country does a great deal to modify its climate. The draining of
bogland and the destruction of forest have made Forfarshire a much
drier region. On the other hand, sheltering plantations have been
fostered, which protect the land from the biting east winds so
common in the spring and early summer months. Fogs and hoar frosts
are not infrequent, and the latter do considerable damage to the
root crops. Most of the lowland part of Forfarshire has a southern
slope, a circumstance that contributes to the geniality of its
climate.
The most recent
rainfall map, published by the Scottish Meteorological Society in
1911, is here reproduced. It embodies investigations that have been
made at 129 stations throughout the country during the forty years
from 1871 to 1910, and at a very much larger number of stations for
shorter periods within that time.
The isohyets, or
lines separating districts that have approximately equal rainfall,
divide Scotland into parts variously shaded according as their mean
annual rainfall increases from 25 to over 100 inches. Study of the
map shows that on the whole the rainfall of Forfarshire ranges from
30 to 35 inches per annum, and that this average is greatly exceeded
as one proceeds westwards.
A few statistics
regarding the rainfall of Forfarshire, more minute than can be shown
on a general map of the country, may here be given.
From this table it appears that the
average rainfall in Forfarshire is 30*29 inches, the highest mean
being 43*17 and the lowest 23‘39- Between 1891 and 1900 the greatest
average rainfall for Scotland was recorded at the Ben Nevis
Observatory, viz. i68-98. From 1871 to 1880 the lowest average was
at Cromarty, viz. 23*18. Maximum and minrmum quantities for any
given year are also interesting. The maximum record for any year
since 1871 is 240' 13 at Ben Nevis Observatory (1898); and the
minimum 14^72 at Pentland Skerries Lighthouse (1895). The
corresponding figures for Forfarshire are: maximum, 54-15 at
Craigton Water Works (1872); minimum, 15^51 (1887) at Montrose
Lighthouse. The year 1911, which the man in the street may have
thought to be abnormally dry, the more exact meteorologist has
pronounced to be very ordinary -n respect of rainfall. But in that
case the rain must have been most unevenly distributed, for in that
year the Dundee district—i.e. southern Forfarshire and the adjacent
parts of Fife— received the smallest quantity of rain in the United
Kingdom, viz. i7'o8 inches. The general conclusion then is that our
county is one of the least rainy parts of Scotland.
The great storm of
December 1879 that wrecked the first Tay Bridge gave Dundee an
unenviable notoriety, and though almost equally violent winds have
since occurred their effects have fortunately been less disastrous.
Wind records kept at Dundee for the decade ending in 1910 show that
the prevailing wind is from the southwest, the same quarter as sent
us these tremendous visitants. Twenty-eight per cent, of the
registered winds have come from that direction; 19 per cent, from
the south-east ; 15 from the north-west; 14 from the west; and 13
from the north-east, one of the most biting experienced; while only
1'9 per cent, blow from the north and 1‘2 from the south. South-easters
predominate in April, May, and June; when it frequently happens that
a warm day with westerly breezes is succeeded towards evening by a
cold blast that rolls up dense, chilly fogs—“the east haar ”—which
envelop the eastern and southern parts of the county and penetrate
to its mountain boundary. For the remaining nine months the
southwest breezes attain the highest records.
The sun is above the
horizon in Britain for about 44OO hours in a year, and of this
possible number of hours of sunshine Forfarshire has enjoyed for the
last ten years an average of 1374^ or more than 31 per cent., which
if distributed equally over the year would allow 3§ hours to each
day. The highest record is 1480 in 1905 and the lowest 1236 in 1902.
Monthly averages range from 184'1 hours in June to 40'6 in December.
May, June, and July are the brightest months; and November,
December, and January the dreariest—a matter of common observation
which scientific research corroborates. |