Gatineau Gliding Club
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Gatineau Gliding Club clear sky chart from 2005-11-06 to 2024-11-12.

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 Type	Minimum conditions for hour to be usable				Out of hours
	Clear of Clouds	Transparency	Seeing	Sky Brightness
Planetary:	50%	(no limit)	Average	(no limit)	Nighttime Hours
Deep Sky:	70%	Average	(no limit)	5.9	Nighttime Hours
CCD Imaging:	70%	Below Average	Poor	(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

By Month

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 Forecast	Data Points
Cloud Cover	Day	17% 10% 3 8% 5% 5% 5% 4 5% 7% 33%	101622
	Night	18% 11% 4 8% 5% 4 4 3 5% 6% 32%	97572
Transparency	Day	49% 7% 13% 21% 9% 1	105092
	Night	52% 6% 12% 19% 9% 1	102191
Seeing	Day	21% 9% 27% 25% 13% 4	14530
	Night	22% 7% 26% 32% 11% 1	23556

By Month

Percentage Cloud Cover NE (2006-)
Color Meanings: Overcast 90% covered 80% covered 70% covered 60% covered 50% covered 40% covered 30% covered 20% covered 10% covered Clear
Month	Days in Month		Occurrence of each Forecast	Data Points
January	1st to 10th	Day	17% 17% 5% 13% 6% 5% 5% 3 4 4 21%	2517
	11th to 20th	Day	15% 12% 6% 13% 6% 5% 5% 3 6% 5% 23%	2520
	21st to end	Day	14% 18% 6% 11% 5% 6% 5% 4 5% 6% 19%	2815
February	1st to 10th	Day	14% 15% 4 12% 6% 5% 4 3 5% 5% 26%	1710
	11th to 20th	Day	14% 15% 5% 11% 7% 4 5% 3 4 5% 27%	1699
	21st to end	Day	20% 13% 4 9% 6% 5% 4 4 5% 5% 25%	1570
March	1st to 10th	Day	20% 13% 4 9% 6% 5% 4 3 4 5% 26%	3116
	11th to 20th	Day	13% 15% 5% 10% 6% 5% 5% 3 5% 5% 27%	3410
	21st to end	Day	15% 7% 2 7% 6% 4 5% 3 4 6% 40%	4070
April	1st to 10th	Day	21% 12% 4 7% 4 4 3 4 4 5% 33%	2280
	11th to 20th	Day	21% 9% 3 6% 4 4 4 3 4 6% 35%	2254
	21st to end	Day	22% 10% 3 8% 5% 5% 4 3 3 6% 30%	2411
May	1st to 10th	Day	20% 8% 3 8% 5% 4 5% 4 6% 7% 29%	4426
	11th to 20th	Day	18% 9% 3 8% 5% 4 4 4 4 7% 33%	4398
	21st to end	Day	16% 7% 2 6% 5% 5% 5% 4 6% 7% 37%	4837
June	1st to 10th	Day	22% 8% 3 7% 5% 5% 4 4 6% 7% 30%	2660
	11th to 20th	Day	13% 7% 2 6% 5% 5% 5% 5% 7% 7% 37%	2660
	21st to end	Day	20% 7% 2 7% 4 5% 5% 5% 7% 7% 31%	2660
July	1st to 10th	Day	12% 7% 2 7% 6% 5% 5% 5% 7% 9% 34%	4440
	11th to 20th	Day	13% 6% 2 6% 5% 4 6% 4 7% 9% 37%	4440
	21st to end	Day	10% 6% 2 5% 4 4 5% 4 6% 9% 44%	4814
August	1st to 10th	Day	14% 7% 3 8% 5% 5% 5% 4 7% 8% 35%	4423
	11th to 20th	Day	16% 6% 2 6% 4 4 4 4 6% 9% 38%	3958
	21st to end	Day	15% 5% 2 6% 4 4 5% 3 7% 9% 39%	4180
September	1st to 10th	Day	14% 6% 2 5% 4 4 5% 5% 6% 7% 43%	2280
	11th to 20th	Day	13% 5% 1 5% 4 3 4 4 6% 7% 49%	2253
	21st to end	Day	17% 7% 2 5% 4 4 4 4 5% 7% 41%	2070
October	1st to 10th	Day	20% 9% 3 6% 4 3 4 3 5% 7% 36%	1900
	11th to 20th	Day	20% 11% 3 8% 5% 5% 5% 3 5% 6% 29%	1900
	21st to end	Day	25% 9% 3 7% 5% 5% 4 3 4 6% 28%	1901
November	1st to 10th	Day	16% 9% 2 7% 5% 5% 5% 4 5% 7% 34%	1761
	11th to 20th	Day	19% 13% 4 9% 5% 5% 4 3 5% 6% 28%	1571
	21st to end	Day	22% 13% 4 9% 6% 6% 4 4 4 7% 22%	1520
December	1st to 10th	Day	23% 16% 4 10% 6% 6% 5% 4 5% 5% 18%	1520
	11th to 20th	Day	21% 16% 4 10% 5% 4 4 3 4 5% 25%	1906
	21st to end	Day	27% 19% 4 10% 5% 3 3 2 3 3 20%	2772
January	1st to 10th	Night	18% 17% 6% 11% 6% 5% 4 3 4 5% 22%	4429
	11th to 20th	Night	14% 14% 5% 13% 7% 6% 5% 4 6% 5% 22%	4440
	21st to end	Night	16% 21% 6% 11% 5% 5% 4 3 4 5% 22%	4838
February	1st to 10th	Night	14% 14% 6% 11% 6% 6% 6% 4 5% 5% 24%	2470
	11th to 20th	Night	13% 13% 4 11% 6% 5% 5% 4 4 5% 29%	2366
	21st to end	Night	17% 13% 4 9% 6% 4 5% 3 5% 6% 29%	1884
March	1st to 10th	Night	21% 11% 5% 9% 5% 4 4 3 4 4 31%	3724
	11th to 20th	Night	17% 16% 4 9% 5% 4 4 3 4 6% 27%	3547
	21st to end	Night	15% 11% 3 8% 4 3 4 3 5% 5% 39%	3562
April	1st to 10th	Night	22% 11% 2 7% 4 4 4 3 4 5% 32%	1900
	11th to 20th	Night	19% 10% 3 7% 5% 5% 3 3 5% 6% 35%	1875
	21st to end	Night	21% 9% 3 7% 4 3 4 3 5% 5% 35%	1783
May	1st to 10th	Night	20% 9% 3 8% 4 5% 4 5% 6% 7% 29%	2514
	11th to 20th	Night	20% 9% 2 7% 4 3 4 3 5% 7% 35%	2495
	21st to end	Night	15% 7% 3 7% 5% 5% 5% 4 6% 7% 37%	2738
June	1st to 10th	Night	16% 7% 2 7% 4 6% 5% 4 8% 9% 31%	1520
	11th to 20th	Night	15% 7% 2 7% 4 4 4 4 6% 8% 40%	1520
	21st to end	Night	18% 8% 2 5% 5% 3 5% 4 7% 7% 35%	1520
July	1st to 10th	Night	13% 7% 3 8% 5% 5% 6% 5% 7% 7% 34%	2520
	11th to 20th	Night	12% 6% 3 7% 4 4 5% 4 7% 8% 41%	2520
	21st to end	Night	11% 6% 2 6% 4 5% 6% 4 6% 7% 43%	2739
August	1st to 10th	Night	13% 7% 3 8% 5% 5% 4 5% 6% 7% 37%	2506
	11th to 20th	Night	15% 6% 2 7% 4 4 4 3 5% 8% 41%	2836
	21st to end	Night	13% 7% 2 6% 5% 4 5% 4 6% 7% 40%	3476
September	1st to 10th	Night	11% 6% 1 7% 5% 4 5% 4 5% 7% 44%	1900
	11th to 20th	Night	15% 5% 1 5% 4 3 3 3 6% 7% 49%	1926
	21st to end	Night	17% 5% 2 6% 4 5% 4 3 4 7% 44%	2108
October	1st to 10th	Night	19% 8% 3 6% 4 4 3 4 5% 6% 38%	2280
	11th to 20th	Night	20% 8% 3 7% 5% 6% 4 3 5% 6% 33%	2280
	21st to end	Night	22% 10% 3 9% 6% 4 4 3 5% 6% 29%	2696
November	1st to 10th	Night	20% 9% 3 7% 5% 4 4 3 5% 6% 33%	2537
	11th to 20th	Night	19% 11% 3 8% 5% 5% 5% 3 5% 5% 30%	2631
	21st to end	Night	22% 12% 4 9% 6% 5% 3 3 5% 5% 24%	2660
December	1st to 10th	Night	21% 16% 7% 10% 5% 5% 5% 4 4 5% 19%	2660
	11th to 20th	Night	23% 15% 4 8% 5% 4 4 3 4 4 26%	3288
	21st to end	Night	31% 18% 4 9% 4 3 3 2 4 3 19%	4884

Transparency (when cloud cover <= 30%)
Color Meanings: Too cloudy to forecast Poor Below Average Average Above average Transparent
Month	Days in Month		Occurrence of each Forecast	Data Points
January	1st to 10th	Day	63% 10% 10% 11% 5% 1	2518
	11th to 20th	Day	61% 6% 12% 15% 6% 1	2520
	21st to end	Day	65% 7% 12% 10% 5%	2815
February	1st to 10th	Day	59% 5% 10% 19% 5% 2	1710
	11th to 20th	Day	57% 6% 12% 15% 9% 1	1708
	21st to end	Day	59% 6% 10% 13% 11% 1	1570
March	1st to 10th	Day	59% 6% 9% 17% 9% 1	3119
	11th to 20th	Day	56% 7% 12% 15% 9% 2	3410
	21st to end	Day	43% 7% 8% 21% 18% 3	4070
April	1st to 10th	Day	54% 5% 8% 19% 12% 3	2280
	11th to 20th	Day	50% 5% 7% 22% 14% 2	2254
	21st to end	Day	55% 5% 9% 14% 13% 4	2411
May	1st to 10th	Day	50% 8% 9% 21% 9% 2	4440
	11th to 20th	Day	49% 8% 14% 19% 9% 1	4402
	21st to end	Day	42% 8% 13% 22% 14% 1	4837
June	1st to 10th	Day	53% 6% 11% 19% 11% 1	2660
	11th to 20th	Day	43% 7% 12% 23% 13% 2	2660
	21st to end	Day	49% 9% 13% 19% 10% 1	2660
July	1st to 10th	Day	43% 7% 14% 24% 11% 1	4370
	11th to 20th	Day	40% 7% 15% 29% 8%	4365
	21st to end	Day	35% 7% 15% 32% 11%	4661
August	1st to 10th	Day	45% 7% 16% 22% 9%	4409
	11th to 20th	Day	42% 7% 15% 29% 7%	3997
	21st to end	Day	41% 7% 17% 22% 12% 1	4180
September	1st to 10th	Day	38% 7% 15% 27% 13%	2280
	11th to 20th	Day	34% 6% 14% 31% 14% 1	2253
	21st to end	Day	42% 6% 15% 27% 10%	2070
October	1st to 10th	Day	46% 6% 12% 28% 7%	3160
	11th to 20th	Day	46% 6% 15% 26% 7%	3140
	21st to end	Day	48% 5% 19% 22% 6%	3113
November	1st to 10th	Day	49% 6% 15% 22% 7% 1	1761
	11th to 20th	Day	57% 5% 13% 15% 9%	1571
	21st to end	Day	62% 7% 13% 13% 5%	1520
December	1st to 10th	Day	68% 6% 12% 11% 3	1520
	11th to 20th	Day	63% 6% 13% 14% 4	1906
	21st to end	Day	71% 4 8% 13% 4	2772
January	1st to 10th	Night	65% 7% 14% 10% 4	4429
	11th to 20th	Night	62% 8% 14% 11% 5%	4440
	21st to end	Night	66% 5% 12% 11% 6% 1	4838
February	1st to 10th	Night	60% 6% 11% 17% 6% 1	2470
	11th to 20th	Night	57% 6% 10% 19% 8%	2368
	21st to end	Night	55% 5% 10% 18% 11%	1884
March	1st to 10th	Night	55% 6% 9% 18% 10% 3	3734
	11th to 20th	Night	58% 5% 12% 15% 8% 2	3548
	21st to end	Night	45% 6% 7% 23% 16% 3	3562
April	1st to 10th	Night	53% 5% 9% 17% 14% 2	1900
	11th to 20th	Night	49% 6% 8% 21% 15% 1	1875
	21st to end	Night	50% 4 9% 17% 16% 4	1783
May	1st to 10th	Night	51% 8% 11% 18% 9% 3	2520
	11th to 20th	Night	46% 9% 11% 19% 13% 2	2496
	21st to end	Night	42% 9% 12% 18% 17% 2	2739
June	1st to 10th	Night	47% 8% 14% 20% 11% 1	1520
	11th to 20th	Night	42% 6% 12% 21% 17% 2	1520
	21st to end	Night	45% 9% 13% 19% 14% 1	1520
July	1st to 10th	Night	45% 8% 14% 19% 12% 1	2480
	11th to 20th	Night	39% 6% 16% 31% 8%	2472
	21st to end	Night	38% 7% 16% 25% 14%	2651
August	1st to 10th	Night	44% 7% 15% 26% 8%	2496
	11th to 20th	Night	41% 6% 16% 30% 7%	2863
	21st to end	Night	41% 8% 15% 23% 12% 2	3476
September	1st to 10th	Night	38% 7% 12% 27% 15% 1	1900
	11th to 20th	Night	35% 6% 13% 34% 11% 1	1926
	21st to end	Night	40% 5% 14% 29% 12%	2108
October	1st to 10th	Night	43% 6% 15% 26% 10%	3800
	11th to 20th	Night	45% 6% 14% 26% 9%	3779
	21st to end	Night	48% 6% 17% 20% 10%	4434
November	1st to 10th	Night	51% 5% 14% 20% 8% 1	2537
	11th to 20th	Night	54% 7% 12% 18% 9% 1	2631
	21st to end	Night	61% 7% 13% 15% 5%	2660
December	1st to 10th	Night	68% 5% 10% 13% 4	2660
	11th to 20th	Night	61% 5% 9% 16% 7% 1	3288
	21st to end	Night	70% 5% 8% 13% 4	4884

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
Month	Days in Month		Occurrence of each Forecast	Data Points
January	1st to 10th	Day	27% 12% 26% 29% 6% 2	180
	11th to 20th	Day	22% 12% 36% 24% 5% 2	180
	21st to end	Day	19% 9% 32% 31% 8% 1	213
February	1st to 10th	Day	29% 13% 38% 16% 4	270
	11th to 20th	Day	23% 15% 37% 23% 2	306
	21st to end	Day	27% 11% 31% 28% 3	382
March	1st to 10th	Day	23% 10% 30% 28% 9%	460
	11th to 20th	Day	20% 16% 32% 26% 5% 1	460
	21st to end	Day	26% 10% 32% 19% 10% 3	506
April	1st to 10th	Day	26% 16% 28% 19% 10% 2	460
	11th to 20th	Day	29% 14% 24% 18% 12% 3	452
	21st to end	Day	26% 12% 31% 18% 11% 2	460
May	1st to 10th	Day	23% 7% 29% 28% 9% 3	463
	11th to 20th	Day	19% 10% 28% 26% 13% 5%	487
	21st to end	Day	18% 9% 31% 25% 14% 4	529
June	1st to 10th	Day	23% 8% 23% 29% 11% 5%	490
	11th to 20th	Day	13% 11% 25% 29% 16% 6%	490
	21st to end	Day	22% 9% 24% 26% 14% 5%	490
July	1st to 10th	Day	13% 6% 22% 33% 19% 7%	485
	11th to 20th	Day	13% 5% 27% 30% 20% 5%	484
	21st to end	Day	14% 4 24% 32% 22% 5%	532
August	1st to 10th	Day	14% 6% 17% 32% 24% 6%	486
	11th to 20th	Day	15% 5% 16% 29% 25% 10%	479
	21st to end	Day	15% 5% 21% 28% 20% 10%	539
September	1st to 10th	Day	17% 5% 24% 23% 18% 13%	490
	11th to 20th	Day	13% 5% 19% 22% 25% 16%	490
	21st to end	Day	19% 7% 26% 21% 18% 9%	490
October	1st to 10th	Day	24% 9% 24% 20% 17% 5%	490
	11th to 20th	Day	23% 14% 28% 22% 12% 1	490
	21st to end	Day	31% 8% 25% 26% 10%	439
November	1st to 10th	Day	24% 12% 25% 25% 12% 2	395
	11th to 20th	Day	25% 10% 33% 23% 7% 2	225
	21st to end	Day	26% 15% 25% 25% 8% 2	180
December	1st to 10th	Day	29% 8% 29% 23% 10%	180
	11th to 20th	Day	24% 15% 37% 21% 3 1	180
	21st to end	Day	33% 12% 34% 15% 6% 1	198
January	1st to 10th	Night	28% 9% 28% 29% 6%	760
	11th to 20th	Night	27% 9% 28% 30% 6% 1	760
	21st to end	Night	19% 7% 29% 36% 8% 1	836
February	1st to 10th	Night	21% 8% 34% 31% 6%	760
	11th to 20th	Night	20% 9% 36% 29% 6%	743
	21st to end	Night	24% 8% 30% 33% 5%	628
March	1st to 10th	Night	23% 9% 29% 32% 7%	760
	11th to 20th	Night	24% 9% 32% 28% 6% 1	760
	21st to end	Night	22% 7% 30% 31% 10%	836
April	1st to 10th	Night	27% 8% 28% 30% 6%	760
	11th to 20th	Night	24% 10% 30% 27% 9% 1	751
	21st to end	Night	26% 7% 27% 30% 8% 1	643
May	1st to 10th	Night	24% 5% 27% 32% 9% 2	380
	11th to 20th	Night	24% 5% 26% 32% 13%	374
	21st to end	Night	16% 6% 30% 34% 14%	411
June	1st to 10th	Night	16% 4 25% 43% 11% 1	380
	11th to 20th	Night	17% 3 26% 40% 12% 1	380
	21st to end	Night	19% 4 24% 35% 17% 1	380
July	1st to 10th	Night	10% 4 21% 45% 19%	370
	11th to 20th	Night	12% 2 20% 45% 20% 1	368
	21st to end	Night	13% 3 16% 47% 19% 1	416
August	1st to 10th	Night	12% 4 14% 47% 22% 1	378
	11th to 20th	Night	15% 4 13% 37% 29% 3	589
	21st to end	Night	14% 3 20% 40% 21% 3	836
September	1st to 10th	Night	14% 4 20% 41% 20% 1	760
	11th to 20th	Night	17% 5% 15% 34% 27% 3	760
	21st to end	Night	18% 4 22% 32% 22% 2	760
October	1st to 10th	Night	23% 5% 24% 31% 17% 1	760
	11th to 20th	Night	25% 7% 25% 32% 10% 1	760
	21st to end	Night	25% 9% 25% 33% 7%	836
November	1st to 10th	Night	24% 9% 24% 31% 11% 1	780
	11th to 20th	Night	24% 9% 31% 25% 10%	765
	21st to end	Night	27% 9% 29% 26% 9%	760
December	1st to 10th	Night	29% 9% 29% 28% 6%	760
	11th to 20th	Night	28% 11% 29% 25% 6% 1	760
	21st to end	Night	35% 8% 29% 23% 4	836

Page generated at 2024-11-08 22:45:40. Version ac07

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