Waid Observatory (Margate)
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Waid Observatory (Margate) clear sky chart from 2005-11-05 to 2017-10-31.

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
64%
16451
16%
47445
14%
16412
67%
16412
26%
31569

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
54%
716
15%
2327
12%
716
60%
716
22%
1493
January16th to endNight
56%
768
22%
2484
19%
768
63%
768
29%
1480
February1st to 15thNight
55%
703
25%
2092
21%
700
61%
700
33%
1243
February16th to endNight
62%
631
27%
1735
20%
631
68%
631
37%
1034
March1st to 15thNight
58%
720
24%
1980
16%
720
65%
720
38%
1172
March16th to endNight
63%
768
23%
2112
19%
768
66%
768
37%
1269
April1st to 15thNight
72%
718
23%
1970
20%
718
74%
718
44%
1104
April16th to endNight
65%
720
22%
1800
14%
720
68%
720
37%
1127
May1st to 15thNight
76%
719
23%
1799
15%
719
77%
719
45%
1054
May16th to endNight
69%
617
14%
1739
12%
617
69%
617
26%
1210
June1st to 15thNight
64%
540
8%
1620
7%
540
64%
540
16%
1240
June16th to endNight
78%
540
8%
1620
7%
540
78%
540
21%
1160
July1st to 15thNight
70%
510
5%
1530
6%
510
70%
510
16%
1154
July16th to endNight
80%
564
9%
1595
9%
531
81%
531
24%
1086
August1st to 15thNight
78%
620
7%
1690
7%
617
78%
617
25%
1170
August16th to endNight
68%
764
6%
1997
5%
764
68%
764
18%
1520
September1st to 15thNight
67%
720
4%
1980
4%
720
67%
720
14%
1560
September16th to endNight
61%
717
6%
1980
6%
717
61%
717
12%
1631
October1st to 15thNight
66%
720
13%
2103
15%
720
66%
720
21%
1492
October16th to endNight
54%
768
17%
2303
16%
768
57%
768
22%
1610
November1st to 15thNight
62%
700
23%
2101
22%
700
66%
700
30%
1310
November16th to endNight
56%
720
20%
2160
18%
720
61%
720
25%
1449
December1st to 15thNight
58%
720
19%
2232
17%
720
61%
720
23%
1484
December16th to endNight
65%
768
21%
2496
21%
768
68%
768
28%
1517

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
9%6%37%7%47%7%8%10%27%
48296
Night
7%425%5%35%6%7%10%39%
47647
TransparencyDay
46%12%15%14%8%2
47997
Night
37%11%18%19%10%3
47449
SeeingDay
8%110%22%29%26%
6260
Night
8%113%29%31%14%
16459

By Month

Percentage Cloud Cover SE (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
12%6%37%6%35%6%7%9%31%
1611
16th to endDay
9%5%35%6%46%5%6%9%35%
1737
February1st to 15thDay
11%7%35%5%35%46%9%37%
1765
16th to endDay
7%5%26%5%36%47%9%42%
1738
March1st to 15thDay
6%426%7%37%6%7%11%37%
1980
16th to endDay
7%435%7%45%5%7%9%36%
2111
April1st to 15thDay
7%425%5%26%6%8%12%36%
1978
16th to endDay
7%5%26%6%47%7%7%10%35%
2160
May1st to 15thDay
43245%46%7%8%9%41%
2152
16th to endDay
10%6%37%8%5%8%7%7%9%24%
2384
June1st to 15thDay
13%7%39%10%6%8%8%7%8%15%
2340
16th to endDay
9%6%38%9%5%10%8%9%10%18%
2340
July1st to 15thDay
9%7%47%8%5%9%9%9%11%18%
2340
16th to endDay
7%6%37%9%48%9%9%12%20%
2465
August1st to 15thDay
9%6%38%7%5%7%9%9%12%20%
2247
16th to endDay
10%7%38%8%48%8%9%11%18%
2202
September1st to 15thDay
9%6%49%8%6%10%9%8%10%15%
1980
16th to endDay
13%9%49%10%6%8%8%7%6%14%
1980
October1st to 15thDay
9%7%47%8%5%8%7%9%10%20%
1856
16th to endDay
14%6%37%6%46%6%7%8%27%
1920
November1st to 15thDay
10%5%36%5%47%6%7%8%35%
1757
16th to endDay
12%5%36%7%47%6%6%6%34%
1800
December1st to 15thDay
12%6%47%7%45%5%5%8%32%
1725
16th to endDay
8%5%35%6%36%6%8%10%35%
1728
January1st to 15thNight
10%5%25%5%35%6%7%10%37%
2327
16th to endNight
6%324435%6%6%10%44%
2484
February1st to 15thNight
10%42442346%8%47%
2086
16th to endNight
5%225%4245%6%9%51%
1735
March1st to 15thNight
5%324425%5%6%9%50%
1980
16th to endNight
5%3235%345%5%11%48%
2112
April1st to 15thNight
32133335%6%11%55%
1970
16th to endNight
6%4244246%8%8%47%
1800
May1st to 15thNight
33133346%6%10%54%
1799
16th to endNight
7%5%346%37%5%8%11%33%
1738
June1st to 15thNight
12%5%26%6%46%8%9%11%24%
1620
16th to endNight
4415%6%5%7%7%9%13%32%
1620
July1st to 15thNight
6%447%6%47%5%9%9%32%
1620
16th to endNight
3325%6%46%6%8%11%40%
1703
August1st to 15thNight
6%3145%36%7%8%13%38%
1701
16th to endNight
8%5%26%6%47%8%9%11%29%
1997
September1st to 15thNight
7%6%27%7%5%8%8%9%13%23%
1980
16th to endNight
10%6%28%8%6%7%9%9%9%22%
1980
October1st to 15thNight
7%5%26%7%5%7%6%9%12%29%
2103
16th to endNight
14%6%25%6%35%5%6%8%34%
2303
November1st to 15thNight
7%325%6%345%6%9%44%
2101
16th to endNight
10%5%35%5%46%46%9%37%
2160
December1st to 15thNight
9%5%25%6%35%6%7%10%38%
2232
16th to endNight
7%424436%5%7%9%45%
2496

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
45%9%13%13%12%4
1612
16th to endDay
41%8%11%18%14%5%
1737
February1st to 15thDay
40%6%11%20%15%5%
1767
16th to endDay
35%7%13%22%14%6%
1738
March1st to 15thDay
37%8%15%21%14%2
1980
16th to endDay
38%9%14%18%14%5%
2112
April1st to 15thDay
35%8%17%21%14%2
1978
16th to endDay
39%8%13%19%16%3
2160
May1st to 15thDay
33%9%14%23%13%5%
2152
16th to endDay
50%13%13%16%6%
2388
June1st to 15thDay
61%12%12%9%3
2340
16th to endDay
53%17%18%9%
2340
July1st to 15thDay
52%20%20%7%
2201
16th to endDay
47%20%22%8%
2310
August1st to 15thDay
46%20%21%10%1
2234
16th to endDay
51%18%19%8%
2202
September1st to 15thDay
55%20%16%6%1
1980
16th to endDay
62%17%11%5%3
1980
October1st to 15thDay
51%13%15%11%6%1
1856
16th to endDay
50%9%10%13%11%5%
1920
November1st to 15thDay
42%8%11%16%16%4
1757
16th to endDay
48%7%11%10%16%6%
1800
December1st to 15thDay
47%8%12%15%13%2
1725
16th to endDay
40%8%13%18%15%3
1728
January1st to 15thNight
40%8%17%19%11%2
2327
16th to endNight
32%8%16%22%13%5%
2484
February1st to 15thNight
33%5%11%26%16%6%
2094
16th to endNight
28%8%14%26%16%5%
1735
March1st to 15thNight
28%7%16%23%18%5%
1980
16th to endNight
29%7%17%24%15%4
2112
April1st to 15thNight
22%8%20%29%16%2
1970
16th to endNight
30%8%16%22%17%4
1800
May1st to 15thNight
24%7%15%33%14%5%
1800
16th to endNight
40%11%19%22%6%
1740
June1st to 15thNight
48%15%19%13%3
1620
16th to endNight
37%18%29%12%1
1620
July1st to 15thNight
45%17%26%10%
1530
16th to endNight
32%18%32%14%2
1595
August1st to 15thNight
33%18%30%16%1
1690
16th to endNight
41%20%24%11%
1997
September1st to 15thNight
45%21%22%9%1
1980
16th to endNight
52%19%15%8%3
1980
October1st to 15thNight
43%12%19%15%8%1
2103
16th to endNight
46%7%12%16%11%5%
2303
November1st to 15thNight
36%6%13%19%17%5%
2101
16th to endNight
42%7%13%14%14%7%
2160
December1st to 15thNight
40%10%14%16%15%2
2232
16th to endNight
33%9%13%22%17%3
2496

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
18%8%17%30%24%
90
16th to endDay
14%9%20%36%12%6%
96
February1st to 15thDay
11%17%40%23%5%
106
16th to endDay
8%224%39%24%1
239
March1st to 15thDay
4127%40%21%4
270
16th to endDay
6%121%38%26%5%
288
April1st to 15thDay
4118%34%30%10%
270
16th to endDay
7%10%35%35%10%
270
May1st to 15thDay
417%29%41%15%
288
16th to endDay
8%16%15%36%31%
331
June1st to 15thDay
11%16%17%32%31%
315
16th to endDay
437%28%56%
315
July1st to 15thDay
6%5%29%57%
305
16th to endDay
328%26%57%
326
August1st to 15thDay
6%37%25%55%
313
16th to endDay
11%211%27%46%
332
September1st to 15thDay
9%212%20%54%
315
16th to endDay
12%1113%27%43%
314
October1st to 15thDay
9%10%22%40%16%
315
16th to endDay
13%318%30%21%12%
336
November1st to 15thDay
10%13%29%32%13%
265
16th to endDay
8%121%34%30%2
270
December1st to 15thDay
16%217%29%29%4
195
16th to endDay
11%12%28%40%7%
96
January1st to 15thNight
10%419%34%27%2
720
16th to endNight
7%424%41%21%1
768
February1st to 15thNight
10%323%41%19%
704
16th to endNight
6%222%48%20%
631
March1st to 15thNight
6%225%39%23%2
720
16th to endNight
5%120%45%24%1
768
April1st to 15thNight
4113%46%30%3
718
16th to endNight
8%15%43%30%1
720
May1st to 15thNight
4110%43%37%2
720
16th to endNight
7%18%29%40%12%
619
June1st to 15thNight
10%25%17%39%23%
540
16th to endNight
3310%42%39%
540
July1st to 15thNight
6%210%40%40%
510
16th to endNight
317%36%49%
564
August1st to 15thNight
7%17%44%39%
620
16th to endNight
9%311%36%38%
764
September1st to 15thNight
8%15%11%35%37%
720
16th to endNight
12%412%37%32%
717
October1st to 15thNight
9%18%28%40%12%
720
16th to endNight
17%114%29%27%10%
768
November1st to 15thNight
9%117%34%31%5%
700
16th to endNight
12%219%34%26%3
720
December1st to 15thNight
10%319%35%28%2
720
16th to endNight
7%217%33%33%5%
768
Page generated at 2017-11-01 17:23:38. Version ac04

Copyright 2017 A. Danko


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