Ceilometer CT25K
User’s Guide CT25K-U059en-2.1
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Then select the sky condition message type (msg6 or msg7) to be reported:
CEILO>set message type msg6
MESSAGE TYPE: 6
CEILO>close
NOTE
It is recommended to use a 15 or 30 seconds data
acquisition interval with the sky condition option.
5.4.4 Algorithm overview
The sky condition algorithm collects data for 30 minutes. All cloud heights
are rounded to the nearest 50 ft or 10 m and a weight factor is assigned. Each
measurement has a total weight of five which is divided between different
cloud layers according to table 5-3.
1st layer 2st layer 3rd layer
1 layer detected 5 - -
2 layers detected 3 2 -
3 layers detected 3 1 1
Table 5-3 Weight factors
In addition, a weight factor of 2 is applied to the data collected during the last
10 minutes to make the algorithm more responsive to variations in cloudiness.
The weighted cloud hits, counts, are assigned to the cloud height categories or
bins (i.e. 0 ... 100 ft, 100 ft ... 200 ft etc.). The bin width increases with the
distance according to table 5-4.
Height Bin width
0-5000 ft 100 ft
5000-15000 ft 500 ft
15000-25000 ft 1000 ft
Table 5-4 Bin widths
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