APPLIED CLIMATOLOGY 
built to withstand the elements for half-a-century or 
more. Hence the most probable values and the extremes 
of climatic elements must be known. As almost all 
climatic elements are involved, there will have to be 
compromises. For example, a roof design best for good 
drainage of rainfall and for avoiding excessive ac- 
cumulations of snow may result in undesirably high 
absorption of solar radiation in summer. But at least 
the designer should have the basic information on 
climate available, so that he can plan for optimal 
results. 
Even though the side-by-side data on all the climatic 
elements are valuable, they are by no means the final 
solution for problems of housing climatology. This is 
best illustrated by the specific case of heating require- 
ments. Insulation and heating plants are commonly 
planned on the basis of heating degree days.? This factor 
is a derivative of temperature alone but is supposed to 
be an index for the heat loss of a house. Obviously, 
there is correlation between the temperature gradient 
“«ndoors-outdoors” and the heating required. Yet the 
degree-day index completely neglects the radiation and 
wind factors. The latter is quite important. Hence the 
design engineer would prefer to get from the climatol- 
ogist a suitably combined factor of temperature and 
wind speed, reflecting the total cooling power of the 
atmosphere. Such joint relationships have been elabo- 
rated by the use of test houses [43]. However, this factor 
is neither directly measured nor generally used in de- 
sign, because it is not usually known to both architects 
and meteorologists. This factor can be calculated ap- 
proximately from simultaneous observations of temper- 
ature and wind speeds. But wind observations obtained 
on airport towers or other high structures are not 
directly applicable. They have to be reduced to the 
height of the building for which the design values are 
desired. For this purpose one can safely assume a 
logarithmic distribution of wind speed with height. 
Somewhat more refined aerodynamic procedures are 
also available in case very high accuracy is needed 
[69]. These calculations should not be applied to mean 
values of temperature and wind because in all practical 
cases the frequency distribution of cooling power is 
actually needed and, furthermore, at many stations 
there exist peculiar interrelations of temperature and 
wind speeds. At present these calculations are some- 
what tedious, but they could easily be reduced to a 
minimum because the pertinent equations are readily 
adaptable to nomographic solutions. 
We run into an analogous problem when evaluating 
climatic data for clothing design or issue. Several as- 
pects of this last problem have recently been discussed 
in the literature [9, 18, 22, 60, 82]. The dry atmospheric 
cooling power in the shade as a function of wind speed 
and temperature has been measured as well as cal- 
culated. Among the measuring devices, the frigorigraph 
of Bittner and Pfleiderer has undergone rigid tests 
2. Heating degree-days per day = 65F minus actually ob- 
served mean temperature for the day when below 65F. 
Heating degree-days per month or year = cumulative 
values of degree-days per day. 
983 
[48] and proved to be a rather satisfactory instrument 
for climatological purposes. Very few stations have 
this, or even more primitive types of equipment such 
as the katathermometer, and series of records are 
scarce. Therefore, for some time to come, climatic 
problems in clothing design have to be solved by 
means of the empirical formulas developed by Hill, 
Bittner, Plummer, Siple, and others. These are fairly 
satisfactory for the dry cooling power and they are 
reduced to nomographic form [6C, p. 202]. These formu- 
las, however, cover only part of the heat or cold stress 
problem. Radiation influence is neglected and evapora- 
tive cooling from sweating is not included. Formulas 
considering these additional terms are much less re- 
liable for conversion of climatological data into values 
applicable to clothing problems. The experimental 
bodies used in establishing the relations give only a 
very poor first-order approximation of human physio- 
logical reactions. The real physiological process includes 
such complicated functions as the effect of body position 
on radiative heat exchange and the effect of rate of 
activity on sweating and hence evaporative cooling. 
These factors cannot be reduced readily to universally 
applicable quantitative terms that can be translated 
into the simple climatic elements which are observed at 
many stations. A further complication is that no stand- 
ard human being exists. Individual reactions to en- 
vironment cover a broad band. Studies on various 
types of individuals, registering their subjective feeling 
of comfort, will have to be made in order to provide the 
link for the proper interpretation of climatic data. 
A start io this direction is contained in the formulas 
proposed by Burton [16]. These are designed to give 
the effect of clothing on heat loss from the surface of 
the human body. It has been pointed out that these 
formulas apply only to equilibrium conditions. They 
make no allowance for convection inside the clothing, 
nor are the empirical constants of the equations well 
determined. From theoretical considerations Lee has 
arrived at some qualitative criteria for the design of 
tropical clothing. The complexity of clothing design can 
be grasped from a list of the climatic conditions and the 
clothing factors (Table V). 
Taste V. Curirmatic AND CLorHine Factors In TROPICAL 
CxLoTHING DrEsIGN 
Solar radiation, radiation from hot 
objects, hot dry air, hot humid 
air, tropical rain 
Climatic factors......... 
Color, texture, thickness, permea- 
bility for water vapor, weight, 
extent of body covering, open- 
ings, fit, water repellency, under- 
wear 
Clothing factors......... 
Quantitative solutions for five to ten variables, as 
listed in Table V, are not yet within reach. As in the 
case of housing design, microclimatic problems are en- 
countered; for example, the reduction of shelter-meas- 
ured temperatures to various body heights and the 
application of wind data from the usual meteorological 
exposures to “surface-near” data. The difficulty of ob- 
