Kelvin Camp
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Kelvin Camp clear sky chart from 2005-11-05 to 2018-01-20.

This page is a summary of past forecasts. Even though it's based only on forecasts, some people use these pages as clue to a site's climate. But climate data based on actual observation should be preferred (if you can find it!).

Cloud, Transparency and Seeing forecasts are summarized individually. But because good observing conditions require a combination of minimum cloud cover, transparency and seeing, the individual forecast summaries can be difficult to interpret. The observing conditions section counts the combinations of conditions needed for common types of astronomical observation.

Observing Conditions

The following tables count the occurrence of the combinations of forecast and darkness conditions needed for different observations. Conditions are rated by by what percentage of the hours the observation would likely be attempted are usable.
Observation TypeMinimum conditions for hour to be usableOut of hours
Clear of CloudsTransparencySeeingSky Brightness
Planetary:50%(no limit)Average(no limit)Nighttime Hours
Deep Sky:70%Average(no limit)5.9Nighttime Hours
CCD Imaging:70%Below AveragePoor(no limit)Nighttime Hours

Percentages are of nighttime hours per month, or per year, when a particular observing conditions was met. Deep Sky percentages never exceed 50% because the moon is up half the time. Deep sky percentages are much lower for charts at high latitudes because of fewer dark hours in the summer.

Overall

PlanetaryData
Pts
Deep Sky
Max 60%
Data
Pts
Both Planetary and Deep Sky
Max 60%
Data
Pts
Either Planetary or Deep SkyData
Pts
CCD ImagingData
Pts
Night
44%
15289
7%
48357
5%
15263
45%
15263
14%
36594

By Month

MonthDays of MonthPlanetaryData
Pts
Deep Sky
Max 60%
Data
Pts
Both Planetary and Deep Sky
Max 60%
Data
Pts
Either Planetary or Deep SkyData
Pts
CCD ImagingData
Pts
January1st to 15thNight
46%
1015
9%
3534
7%
1015
49%
1015
15%
2550
January16th to endNight
43%
1022
11%
3345
9%
1022
47%
1022
15%
2476
February1st to 15thNight
50%
874
13%
2637
10%
873
53%
873
20%
1847
February16th to endNight
44%
684
11%
2150
8%
684
48%
684
16%
1603
March1st to 15thNight
61%
720
17%
2213
15%
720
63%
720
26%
1434
March16th to endNight
58%
705
14%
2046
11%
704
61%
704
24%
1429
April1st to 15thNight
56%
539
10%
1597
8%
539
57%
539
28%
1035
April16th to endNight
59%
438
0%
1338
0%
438
59%
438
26%
874
May1st to 15thNight
49%
359
0%
1041
0%
359
49%
359
20%
735
May16th to endNight
50%
244
0%
805
0%
244
50%
244
18%
562
June1st to 15thNight
57%
180
0%
570
0%
180
57%
180
27%
356
June16th to endNight
56%
180
0%
540
0%
180
56%
180
26%
350
July1st to 15thNight
51%
170
0%
540
0%
170
51%
170
20%
357
July16th to endNight
63%
336
0%
845
0%
314
64%
314
29%
566
August1st to 15thNight
62%
360
0%
1117
0%
358
62%
358
23%
750
August16th to endNight
45%
493
1%
1472
0%
493
45%
493
16%
1111
September1st to 15thNight
45%
540
4%
1701
3%
540
47%
540
18%
1206
September16th to endNight
31%
660
6%
1976
4%
660
32%
660
11%
1602
October1st to 15thNight
24%
742
3%
2231
2%
742
25%
742
6%
1945
October16th to endNight
17%
960
1%
2700
1%
960
17%
960
3%
2520
November1st to 15thNight
30%
950
2%
3041
2%
950
30%
950
5%
2730
November16th to endNight
39%
1010
3%
3407
3%
1010
40%
1010
8%
2819
December1st to 15thNight
41%
1020
8%
3559
9%
1020
43%
1020
12%
2713
December16th to endNight
45%
1088
9%
3952
10%
1088
47%
1088
12%
3024

Individual Forecasts

The length of each colored bar in the "occurrence of each Forecast" column is proportional to the number of times the chart forecast that color. The percentages are of the total number of hours per month, or per year, with a particular forecast. The colors as the same as those used in clear sky charts.

Note: Transparency probabilities are only counted for those hours that have 30% or less cloud cover. Seeing probabilities are only counted for those hours that have 80% or less cloud cover. If that's too tricky, try Observing Conditions instead.

Overall

Occurrence of each ForecastData
Points
Cloud CoverDay
11%10%5%8%8%46%5%6%7%24%
49265
Night
9%11%5%9%9%46%7%7%8%20%
48443
TransparencyDay
55%5%14%18%4
48850
Night
57%6%14%16%4
48363
SeeingDay
16%315%28%25%10%
7475
Night
14%317%31%25%7%
15301

By Month

Percentage Cloud Cover NW (2006-)
Color Meanings:
Overcast 90% covered 80% covered 70% covered 60% covered 50% covered 40% covered 30% covered 20% covered 10% covered Clear
MonthDays in MonthOccurrence of each ForecastData
Points
January1st to 15thDay
5%10%26%9%5%9%6%10%12%19%
732
16th to endDay
6%14%48%9%5%7%8%8%7%18%
981
February1st to 15thDay
28%49%9%5%7%7%9%10%24%
1225
16th to endDay
410%7%11%11%46%6%8%11%16%
1335
March1st to 15thDay
29%47%8%5%9%7%7%9%28%
1744
16th to endDay
49%5%8%8%5%9%8%8%10%21%
2174
April1st to 15thDay
9%13%48%7%47%6%6%6%24%
2350
16th to endDay
5%9%5%8%10%7%9%7%6%7%22%
2621
May1st to 15thDay
8%11%6%9%8%46%45%8%25%
2909
16th to endDay
12%9%5%9%6%445%5%7%30%
3308
June1st to 15thDay
12%8%47%6%46%46%7%30%
3390
16th to endDay
11%7%36%7%35%5%6%8%35%
3420
July1st to 15thDay
12%7%36%7%46%5%6%7%30%
3387
16th to endDay
10%5%37%7%46%5%6%8%33%
3263
August1st to 15thDay
12%7%37%8%45%5%5%7%31%
2837
16th to endDay
23%9%48%6%4445%6%21%
2730
September1st to 15thDay
17%13%410%6%345%6%6%20%
2259
16th to endDay
19%17%47%5%445%6%5%19%
1982
October1st to 15thDay
19%19%6%12%9%45%43311%
1715
16th to endDay
18%25%10%13%11%442233
1522
November1st to 15thDay
12%17%6%11%11%6%8%45%6%7%
1146
16th to endDay
7%14%7%10%13%6%9%7%6%8%9%
883
December1st to 15thDay
6%13%6%9%7%5%7%10%10%9%14%
728
16th to endDay
6%9%9%12%9%5%8%8%8%8%13%
624
January1st to 15thNight
5%9%5%9%9%47%8%9%12%18%
3534
16th to endNight
411%5%9%9%5%7%8%10%8%18%
3345
February1st to 15thNight
26%38%10%5%8%8%10%12%22%
2628
16th to endNight
211%7%12%9%5%6%6%8%13%15%
2150
March1st to 15thNight
26%48%7%46%6%8%9%34%
2213
16th to endNight
310%47%7%48%7%7%8%30%
2046
April1st to 15thNight
7%8%47%7%25%46%7%38%
1597
16th to endNight
46%47%7%48%5%6%7%35%
1338
May1st to 15thNight
12%11%5%6%6%45%45%7%31%
1040
16th to endNight
10%8%5%8%8%35%5%45%32%
805
June1st to 15thNight
9%8%345%4448%8%37%
570
16th to endNight
10%5%26%6%36%6%6%9%36%
540
July1st to 15thNight
14%6%45%436%6%7%9%31%
572
16th to endNight
8%435%6%36%7%8%10%35%
904
August1st to 15thNight
12%5%25%5%47%6%7%8%33%
1122
16th to endNight
20%9%36%7%3445%6%26%
1472
September1st to 15thNight
14%10%5%8%5%3445%8%29%
1701
16th to endNight
21%14%6%8%5%35%446%19%
1976
October1st to 15thNight
16%21%8%10%9%35%44310%
2231
16th to endNight
21%21%9%14%10%443233
2700
November1st to 15thNight
12%17%7%12%12%6%8%7%5%45%
3041
16th to endNight
6%12%7%10%12%5%9%10%7%7%9%
3407
December1st to 15thNight
5%11%8%10%10%47%7%8%9%15%
3559
16th to endNight
7%11%6%10%9%5%6%8%9%9%14%
3952

Transparency (when cloud cover <= 30%)
Color Meanings:
Too cloudy to forecast Poor Below Average Average Above average Transparent
MonthDays in MonthOccurrence of each ForecastData
Points
January1st to 15thDay
52%5%20%17%3
732
16th to endDay
58%5%10%16%8%
981
February1st to 15thDay
48%6%16%21%7%
1225
16th to endDay
58%5%9%18%6%
1335
March1st to 15thDay
47%414%23%9%
1744
16th to endDay
53%5%12%19%8%
2175
April1st to 15thDay
55%49%19%10%
2350
16th to endDay
56%5%12%20%4
2621
May1st to 15thDay
55%416%19%4
2909
16th to endDay
51%5%12%25%5%
3313
June1st to 15thDay
49%416%23%5%
3390
16th to endDay
45%6%15%25%7%
3420
July1st to 15thDay
48%6%15%24%4
3190
16th to endDay
45%6%20%23%2
3059
August1st to 15thDay
49%6%21%18%4
2817
16th to endDay
62%6%18%10%2
2730
September1st to 15thDay
61%5%20%10%1
2259
16th to endDay
64%7%15%12%1
1982
October1st to 15thDay
76%5%11%6%
1715
16th to endDay
87%25%3
1522
November1st to 15thDay
75%6%9%7%
1146
16th to endDay
68%6%13%9%1
883
December1st to 15thDay
60%7%13%17%1
728
16th to endDay
61%8%12%16%1
624
January1st to 15thNight
52%8%18%18%2
3534
16th to endNight
55%6%12%18%6%
3345
February1st to 15thNight
47%7%15%22%7%
2640
16th to endNight
56%5%12%17%7%
2150
March1st to 15thNight
42%415%25%10%1
2213
16th to endNight
48%411%24%10%1
2049
April1st to 15thNight
42%410%27%15%
1597
16th to endNight
43%415%27%7%
1338
May1st to 15thNight
51%414%20%8%
1041
16th to endNight
53%310%24%7%
805
June1st to 15thNight
41%319%28%7%
570
16th to endNight
42%5%17%23%10%
540
July1st to 15thNight
45%7%17%25%4
540
16th to endNight
37%9%19%29%4
845
August1st to 15thNight
42%8%22%19%6%
1117
16th to endNight
56%6%20%15%1
1472
September1st to 15thNight
51%6%24%15%2
1701
16th to endNight
65%5%13%12%1
1976
October1st to 15thNight
75%5%11%6%1
2231
16th to endNight
86%36%3
2700
November1st to 15thNight
77%7%9%5%
3041
16th to endNight
66%8%15%7%1
3407
December1st to 15thNight
59%7%13%16%2
3559
16th to endNight
59%7%13%17%1
3952

Seeing (when cloud cover <= 80%)
Color Meanings:
Too cloudy to forecast Bad 1/5 Poor 2/5 Average 3/5 Good 4/5 Excellent 5/5
MonthDays in MonthOccurrence of each ForecastData
Points
January1st to 15thDay
118%47%27%5%
55
16th to endDay
29%16%31%22%8%
72
February1st to 15thDay
8%113%30%33%13%
60
16th to endDay
17%8%422%28%18%
74
March1st to 15thDay
5%11%31%33%17%
135
16th to endDay
8%417%35%24%9%
288
April1st to 15thDay
12%318%35%23%5%
302
16th to endDay
9%215%32%33%7%
450
May1st to 15thDay
14%415%26%26%11%
509
16th to endDay
13%216%32%26%8%
705
June1st to 15thDay
15%5%18%29%23%7%
675
16th to endDay
15%415%30%24%9%
675
July1st to 15thDay
13%418%30%24%9%
645
16th to endDay
12%416%31%24%10%
703
August1st to 15thDay
13%311%20%31%19%
532
16th to endDay
29%312%21%22%10%
499
September1st to 15thDay
25%7%18%23%17%7%
315
16th to endDay
25%5%18%25%18%6%
263
October1st to 15thDay
25%214%20%17%18%
135
16th to endDay
39%110%23%16%7%
142
November1st to 15thDay
16%323%20%18%17%
90
16th to endDay
17%36%39%24%8%
58
December1st to 15thDay
24%211%37%13%11%
45
16th to endDay
26%37%37%16%
48
January1st to 15thNight
8%221%33%25%8%
1020
16th to endNight
9%323%35%21%6%
1022
February1st to 15thNight
5%421%31%25%12%
880
16th to endNight
6%320%36%23%9%
684
March1st to 15thNight
5%214%37%29%10%
720
16th to endNight
7%214%33%33%8%
705
April1st to 15thNight
10%216%36%26%7%
539
16th to endNight
7%214%36%31%7%
438
May1st to 15thNight
16%310%29%32%7%
360
16th to endNight
12%415%34%29%3
244
June1st to 15thNight
10%321%33%30%1
180
16th to endNight
13%315%38%27%1
180
July1st to 15thNight
17%414%31%27%4
170
16th to endNight
9%212%39%30%4
336
August1st to 15thNight
15%111%27%33%10%
360
16th to endNight
25%313%24%26%5%
493
September1st to 15thNight
20%416%30%22%5%
540
16th to endNight
29%419%25%16%4
660
October1st to 15thNight
28%416%25%17%7%
742
16th to endNight
31%5%15%22%18%6%
960
November1st to 15thNight
19%6%16%25%23%7%
950
16th to endNight
12%318%33%22%8%
1010
December1st to 15thNight
11%321%34%23%6%
1020
16th to endNight
10%315%30%30%9%
1088
Page generated at 2018-01-21 10:19:26. Version ac04

Copyright 2018 A. Danko


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