JUNE 11, 1914] 
LETTERS TO THE EDITOR. 
[The Editor does not hold himself responsible for 
opinions expressed by his correspondents. Neither 
can he undertake to return, or to correspond with 
the writers of, rejected manuscripts intended for 
this or any other part of Nature. No notice is 
taken of anonymous communications. ] 
Weather Forecasts in England. 
Mr. MaLtock’s position in the scientific world is 
one of distinction and his letters on the subject ot 
weather forecasts in England, which appeared in 
Nature of February 26 and June 4, can, accordingly, 
scarcely fail to be regarded by many who are un- 
familiar with the circumstances as_ reflecting  in- 
juriously upon the department of the public service 
which is in my charge. I ought, therefore, not to let 
them pass unnoticed. 
Let me say that the method of checking forecasts 
employed by Mr. Mallock as described in the letter of 
February 26 would be scouted in the Meteorological 
Office, whatever the result might be, partly because 
the classification of the weather adopted therein is 
quite inadequate, and partly because the conditions at 
a single hour of the day (7 a.m. only) are used as an 
indication of the weather comprised within the period 
of twenty-four hours extending from noon to noon. 
In the Meteorological Office, for checking forecasts, 
the practice was to use three maps for each day in 
conjunction with the schedules of observations col- 
lected for the daily and weekly reports. For the last 
year or two these observations have all been charted, 
so we now use ten maps for each day. Specimens 
were exhibited at the last soirée of the Royal Society. 
The stricter examination is sufficiently encouraging to 
the forecaster. 
No one can wonder that Mr. Mallock revives and 
cherishes an objection to the accumulation of observa- 
tions, because the picture which he draws of the state 
of the atmosphere, and upon which, in his second 
letter, he founds his gloomy forecast of the future of 
forecasting, will not stand comparison with the facts 
of observation. There is no belt of north-east or 
south-east winds all round the globe, as represented 
in Mr. Mallock’s diagram; that notion is a survival 
of times long gone by, and is inconsistent with Buys 
Ballot’s law, as well as the facts set out, for example, 
in Hildebrandsson and Teisserenc de Bort’s ‘‘ Les 
Bases de la Météorologie Dynamique : Historique— 
état de nos connaissances,’’ or, more simply, in ‘‘ The 
Barometer Manual for the Use of Seamen.”’ 
The notion of a collection of eddies in a quiescent 
atmosphere covering the temperate and polar regions 
was also quite familiar to the meteorologists of thirty 
years ago when the vortex theory was as fashionable 
as the quantum theory is now. It derives much sup- 
port from the study of the water of a flowing stream, 
or near a moving ship; only, unfortunately, in the 
atmosphere there are no huge moving ships to cause 
eddies of any diameter up to a thousand miles or 
more; and if there is a flowing stream Mr. Mallock 
does not describe it. There is no machinery round 
the tropic of Cancer, like the popular lecturer’s smoke- 
box, for launching a succession of vortices on a brief 
career of degradation. The theory that cyclonic de- 
pressions are vortices has never led to any real advance 
in our comprehension of the atmosphere, outside the 
region of tropical revolving storms; whereas the close 
study of observations such as those of the Daily 
Weather Report has led, and is leading, slowly but 
surely towards understanding the physics of the 
phenomena. 3 
I should like to suggest to Mr. Mallock and other 
NO. 2328, VOL. 93] 
NATURE 
375 
distinguished men of science who are kind enough to 
take an interest in meteorology, that to stick a pike 
through the front rank of the fighting line in the 
manner recently represented by *‘ Mr. Punch,” is not 
very helpful to the promotion of natural knowledge. 
If they in their turn feel bored by observations, let 
them help us to attack some of the citadels for the 
reduction of which we have very few observations to 
help us. I cannot offer them the surface or the tropo- 
sphere for the purpose; the observations are too 
numerous. But the all-embracing stratosphere is open 
to their imagination with very few observational re- 
strictions. Let me set out my own imperfect idea of 
the problem with the object, not of prolonging this 
correspondence, but of eliciting a valuable contribution 
to knowledge, in the shape of a paper, or even a book. 
Imagine a shell of upper atmosphere containing no 
water-vapour, separated from the moist lower atmo- 
sphere by a smooth surface which, for the time being, 
we will suppose a “level surface.’”” The shell under 
consideration is isothermal or increases in temperature 
upwards, until a region of approximately uniform 
temperature is reached. It is imperfectly transparent 
to radiation, but it has no convection of the ordinary 
local character, and is supposed not to be affected by 
convection from below. In this environment, con- 
siderations of stability may lead us to conclude that 
locally cooled air will find its way over the smooth 
surface towards the equator and locally warmed air 
towards the polar regions. So, we shall get primarily 
a concentration of cold air over the equator and warm 
air over the poles. That, apparently, does really 
occur. The wandering of the air poleward will even- 
tuate in an eastward circulation, the wandering 
towards the equator in a westward circulation. Out- 
side the equatorial region horizontal pressure-differ- 
ences will be balanced by the easterly motion, the 
lines of flow, in the temperate and polar stratosphere, 
being at once isobaric lines and isothermal lines; 
so far as we are able to tell, low pressure is warm 
and high pressure cold. 
What will happen in consequence of the alternate 
solarisation and sky-radiation of this stratosphere by 
day and night I must leave the theoretical theorist to 
say; observation has not yet told us. I will, how- 
ever, venture to suggest that the air cap of the winter 
pole must get colder and colder; ultimately so cold 
that it will wobble and get displaced by warmer air; 
and, yielding to the centrifugal influence, it will slide 
towards the reservoir of cold air over the equatorial 
regions. On its journey it may give rise to easterly 
or northerly currents in the temperate stratosphere 
which are occasionally observed, and which are, at 
present, unexplained. 
Some of the suppositions in the statement which is 
here presented are based on observations with which 
I am familiar, though the guidance that can be got 
from observations in this matter is woefully incom- 
plete; but one, at least, is frankly hypothetical, and 
my question is, whether, from the mathematical point 
of view, the picture may be regarded as true to life 
and, if not, how it should be emended. The problem 
is quite simple compared with that presented by the 
observations of the Daily Weather Report. There is 
no water-vapour, no convection in the ordinary sense, 
and no surface friction. If some philosopher, who 
thinks observations unnecessary, will give us a work- 
ing solution, he will be a real benefactor to meteoro- 
logy; because we know that the stratosphere exerts a 
dominant influence upon the distribution of pressure 
at the surface, which controls our weather, and we 
have no working outline of what happens up there. 
Theory might help us; perhaps Mr. Mallock will 
oblige. 
