EUROPEAN THEATRE
1. Purpose.—This study will indicate
a. The number of days in each month (taking
the average number over a period of years)
when high level bombing over Germany can be carried out.
b. The number of days for a six-months period
beginning with each month of the year (using the average number as in
(a) when high level bombing over Germany can be carried out.
2. Limitations on Bombing Operations.—
a. The limiting values for the ceilings, visibilities, and
cloudiness on high level bombing operations were taken as follows:
(1) Take-off – Ceiling 500
feet
Visib.
½
mile
(2) Landing - Ceiling 1000
feet
Visib.
1 mile
(3) En route – No severe
icing
No
severe turbulence
No
gale winds aloft
(4) Over Target – Ceiling –
unlimited
Clouds
– Three tenths or less of the sky covered.
(5) Daytime operations only.
b. If any of the five targets could be bombed, the day was counted
as an operating day.
c. Only the airdrome area near Upper Heyford was considered as
available for landing or take-off. The more airdromes available and
the more widely dispersed, the more days will be suitable.
3. Method of Investigation —This study is
based on two Independent approaches:
a. A careful examination of the daily weather maps of Europe for
the past five years.
b. A statistical examination of seven years of monthly cloud and
ceiling data for England and Germany.
4. Tables.
a. Table 1—Average number of days per month when the weather
is better than the limiting values (see paragraph 2 a).
|
|
J
|
F
|
M
|
A
|
M
|
Je
|
Jy
|
A
|
S
|
O
|
N
|
D
|
|
Average No. of Days
|
6
|
9
|
12
|
10
|
12
|
12
|
10
|
9
|
10
|
10
|
7
|
6
|
b. Table 2—Average number of days per six (6) month, period
beginning with the month indicated when the weather is better than
the limiting values.
|
|
J
|
F
|
M
|
A
|
M
|
Je
|
Jy
|
A
|
S
|
O
|
N
|
D
|
|
Average No. of Days
|
61
|
65
|
65
|
63
|
63
|
58
|
52
|
48
|
48
|
50
|
50
|
55
|
c. Table 3—The average number of days per month when the
weather is better than the limiting values and in addition when
the sky over the targets is absolutely clear.
|
|
J
|
F
|
M
|
A
|
M
|
Je
|
Jy
|
A
|
S
|
O
|
N
|
D
|
|
Average No. of Days
|
1
|
2
|
6
|
2
|
3
|
7
|
3
|
1
|
2
|
2
|
1
|
1
|
d. Table 4—The average number of days per six months period
when the weather is better than the limiting values and in addition
when the sky over the targets is absolutely clear.
|
|
J
|
F
|
M
|
A
|
M
|
Je
|
Jy
|
A
|
S
|
O
|
N
|
D
|
|
Average No. of Days
|
21
|
23
|
22
|
18
|
18
|
16
|
10
|
8
|
9
|
13
|
13
|
15
|
5. Monthly Variations—
a. The maximum number of days
when the weather will be better than the limiting values will be
about 3 to 4 days more than the average in the winter
and 5 to 6 days more than average in
summer.
b. The minimum number of days
when the weather will be better than the limiting values will be
about 3 days less than the average and 5 to 6
days less than the average in summer.
6. Six-Month Variation—
a. The maximum number of days
for a six-month period during the winter will be about 8 to 10
days more than the average and will be about 14
to 16 days more than the average in summer.
b. The minimum number of days
for a six-month period will be about the same number less than the
average (8 to 10 – winter, 14 to 16 – summer).
Conclusions.
1. The study indicates that even during a season of bad
weather bombing operations from high altitudes can be
carried out on at least 36 days during any six-months period.
2. Within certain limits, the more targets and the
more widely they are dispersed, the more high
altitude bombing raids can be carried out.
3. The governing factor in these high altitude raids
is the amount of cloudiness over the targets. It is to be expected
that with clear or scattered cloudiness over the targets, the
conditions over England will not decrease appreciably the number of
operating days during the summer, but will be a factor on about 40%
of the days in winter. With a small amount of cloudiness over the
target route weather will not cause many cancellations.
4. Within certain limits, the more airdromes available in Great
Britain and the more they are dispersed, the more operations can be
carried out.
5. It is believed that in general, the favorable operating days
will occur in sequences of from two (2) to five (5) consecutive days.
6. The coastal areas will be relatively more favorable for high
altitude bombing operations in summer than the inland regions.
POSSIBLE BOMBING OPERATIONS
FROM
ENGLISH BASES TO OBJECTIVES IN GREATER GERMANY
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The map shows the specific areas used for reference in
obtaining meteorological data. The oval areas were used in
connection with the study of the daily weather maps during a
5-year period. The cities shown were used for reference in a study
of seven years of climatological data. These data came from the
actual observations made at these places over a 7-year period of
time. These data are detailed enough to include ceiling and
percentage of cloud cover.
It is believed that the combination of the daily weather map
study and the climatological data study gives reliable results.
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Prepared By: FORECAST RESEARCH
SECTION
WEATHER
CENTRAL DIVISION
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