METEOROLOGICAL MEASUREMENTS 23 
HEIGHT, FEET 
27 SEPT 1944 
Ficure 8. M curves from New Zealand, east coast near Cook Strait. 
much difference in the types of M curves over land 
‘and over sea except that standard propagation con- 
ditions will in general be much more common over 
land for reasons that will appear in Chapter 5. In 
all these graphs the actually measured points are 
entered so that the reader may gain an idea of the’ 
degree of accuracy obtained with this equipment. 
Figure 3 shows a standard curve as measured at 
the coast of Massachusetts. The linearity of the 
refractive index in this case is not an accident but 
is the result of the definite physical condition of 
thorough turbulent mixing in the lower atmosphere, 
as will be explained in more detail in Chapter 5. 
Since this is a fairly frequent condition, standard 
curves are actually quite common, and in them the 
measuied points cluster well around a straight line 
as shown in Figure 3. 
Figures 4 and 5 show a set of nonstandard curves 
selected from a large series of measurements taken 
on the Massachusetts coast in the summer and fall 
of 1943.4° Here the M curves are quite irregular, 
perhaps more so than is common at other locations. 
These curves show various types of ducts, some of 
them rather weak, others with a decrease of M as 
y 30 NOV 1944 
NEAR SAIPAN 
600 
te 
Ww 
ir 
= 13 OCT 1944 
oS phos NEAR BIAK 
w 
=x 
fo) : 
370 380 390 380 330 400 410 
M 
Figure 9. M curves from the New Guinea area. 
HEIGHT, FEET 
4 
21 NOV 1944 
100 MI NORTH OF 
HUMBOLDT BAY 
se 
Ficure 10. Detailed M curve taken over the ocean near 
New Guinea. 
