Taigh nan Reul
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Taigh nan Reul clear sky chart from 2005-11-06 to 2024-11-10.

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	16% 11% 4 8% 5% 4 4 3 5% 6% 33%	101951
	Night	16% 13% 4 9% 5% 4 4 3 5% 6% 30%	97170
Transparency	Day	50% 6% 12% 21% 10% 1	105532
	Night	54% 6% 11% 19% 10% 1	101666
Seeing	Day	23% 16% 30% 20% 9% 3	14981
	Night	23% 13% 28% 24% 10% 1	23920

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% 22% 12% 11% 4 4 3 2 3 3 19%	2250
	11th to 20th	Day	12% 17% 8% 19% 11% 5% 4 3 4 4 13%	2662
	21st to end	Day	17% 22% 8% 13% 6% 4 3 3 4 4 16%	3124
February	1st to 10th	Day	12% 20% 6% 17% 9% 5% 4 2 3 3 19%	1710
	11th to 20th	Day	13% 16% 7% 12% 6% 5% 4 3 4 5% 25%	1663
	21st to end	Day	18% 17% 7% 10% 6% 5% 5% 3 3 5% 22%	1441
March	1st to 10th	Day	19% 16% 5% 8% 5% 4 3 3 4 5% 29%	3425
	11th to 20th	Day	11% 17% 6% 11% 6% 5% 4 3 4 5% 26%	3480
	21st to end	Day	14% 10% 5% 8% 4 4 3 3 5% 6% 38%	3815
April	1st to 10th	Day	20% 14% 4 8% 5% 4 3 3 4 6% 29%	2245
	11th to 20th	Day	21% 11% 2 6% 4 4 4 3 5% 4 36%	2368
	21st to end	Day	22% 11% 3 7% 4 3 4 3 4 5% 34%	2470
May	1st to 10th	Day	19% 8% 3 6% 4 5% 5% 4 6% 7% 33%	4158
	11th to 20th	Day	14% 9% 2 6% 4 4 4 3 6% 9% 39%	4398
	21st to end	Day	16% 6% 2 5% 4 4 4 4 5% 6% 43%	4837
June	1st to 10th	Day	19% 7% 2 6% 5% 5% 4 4 5% 7% 37%	2675
	11th to 20th	Day	13% 6% 2 6% 5% 4 5% 4 6% 8% 40%	2850
	21st to end	Day	17% 8% 3 6% 5% 4 4 4 6% 7% 36%	2850
July	1st to 10th	Day	14% 6% 3 6% 5% 4 5% 4 7% 9% 37%	4760
	11th to 20th	Day	13% 6% 2 5% 4 4 4 3 6% 7% 45%	4546
	21st to end	Day	10% 5% 2 6% 4 4 4 4 5% 8% 47%	4602
August	1st to 10th	Day	12% 8% 3 7% 4 5% 5% 4 6% 8% 38%	4104
	11th to 20th	Day	16% 6% 3 7% 4 4 5% 4 7% 9% 36%	4044
	21st to end	Day	9% 4 2 6% 4 5% 5% 4 7% 9% 45%	4408
September	1st to 10th	Day	14% 5% 3 6% 4 5% 4 4 6% 7% 41%	2280
	11th to 20th	Day	14% 6% 2 6% 4 4 4 3 6% 7% 45%	2163
	21st to end	Day	18% 8% 3 7% 5% 4 5% 3 6% 6% 35%	2056
October	1st to 10th	Day	21% 7% 3 8% 5% 4 4 4 4 6% 34%	1900
	11th to 20th	Day	26% 10% 3 10% 5% 4 4 3 5% 6% 23%	1900
	21st to end	Day	30% 11% 4 9% 4 4 4 3 5% 5% 21%	2087
November	1st to 10th	Day	19% 15% 4 7% 5% 4 4 3 5% 7% 26%	1609
	11th to 20th	Day	17% 17% 5% 9% 5% 5% 5% 4 6% 5% 21%	1520
	21st to end	Day	21% 21% 3 10% 5% 5% 5% 5% 4 5% 15%	1520
December	1st to 10th	Day	18% 28% 6% 9% 4 4 4 2 3 4 15%	1520
	11th to 20th	Day	19% 22% 7% 11% 5% 3 3 3 4 4 19%	1906
	21st to end	Day	26% 21% 6% 12% 5% 4 4 3 3 4 13%	2605
January	1st to 10th	Night	16% 23% 10% 15% 6% 5% 4 3 3 3 12%	4683
	11th to 20th	Night	14% 16% 6% 17% 8% 6% 6% 3 4 5% 14%	4280
	21st to end	Night	17% 20% 7% 12% 6% 4 4 2 4 4 17%	4532
February	1st to 10th	Night	13% 19% 7% 12% 8% 4 5% 3 5% 6% 19%	2470
	11th to 20th	Night	12% 17% 6% 12% 7% 5% 5% 3 4 5% 24%	2403
	21st to end	Night	17% 16% 5% 10% 7% 5% 4 4 4 5% 24%	2009
March	1st to 10th	Night	16% 14% 5% 8% 5% 4 4 3 4 6% 31%	3413
	11th to 20th	Night	11% 17% 6% 10% 5% 5% 4 3 4 5% 29%	3479
	21st to end	Night	15% 10% 5% 7% 5% 4 4 4 6% 6% 35%	3817
April	1st to 10th	Night	22% 12% 3 8% 5% 4 4 3 4 5% 31%	1934
	11th to 20th	Night	19% 10% 3 8% 3 4 3 3 5% 5% 36%	1777
	21st to end	Night	19% 10% 4 8% 5% 5% 4 4 5% 6% 31%	1710
May	1st to 10th	Night	16% 8% 2 6% 5% 4 4 4 6% 7% 38%	2783
	11th to 20th	Night	16% 7% 2 6% 5% 3 4 4 5% 8% 40%	2495
	21st to end	Night	12% 6% 2 6% 4 4 4 4 5% 8% 44%	2738
June	1st to 10th	Night	16% 7% 3 8% 5% 4 4 4 6% 8% 34%	1500
	11th to 20th	Night	12% 5% 2 5% 5% 4 4 4 5% 10% 44%	1330
	21st to end	Night	16% 7% 3 7% 4 4 4 4 6% 7% 40%	1330
July	1st to 10th	Night	9% 7% 3 8% 4 4 4 4 6% 7% 43%	2210
	11th to 20th	Night	15% 5% 2 5% 3 3 3 3 5% 7% 48%	2413
	21st to end	Night	8% 6% 2 6% 4 4 4 3 5% 8% 50%	2949
August	1st to 10th	Night	11% 6% 2 6% 4 4 5% 4 6% 7% 45%	2825
	11th to 20th	Night	16% 7% 3 6% 4 3 4 3 5% 6% 44%	2785
	21st to end	Night	14% 5% 2 5% 3 3 3 4 5% 7% 48%	3215
September	1st to 10th	Night	10% 6% 3 6% 4 4 4 4 6% 7% 46%	1900
	11th to 20th	Night	13% 5% 2 6% 4 3 3 4 5% 7% 47%	2014
	21st to end	Night	19% 6% 3 6% 5% 4 3 3 5% 6% 39%	2123
October	1st to 10th	Night	19% 8% 3 7% 5% 5% 5% 3 6% 6% 35%	2280
	11th to 20th	Night	25% 11% 3 8% 5% 4 4 3 5% 6% 26%	2280
	21st to end	Night	27% 11% 5% 9% 5% 4 4 3 4 5% 23%	2508
November	1st to 10th	Night	21% 13% 3 7% 5% 4 3 3 4 6% 30%	2673
	11th to 20th	Night	18% 17% 5% 8% 5% 5% 5% 3 5% 6% 23%	2660
	21st to end	Night	23% 19% 5% 10% 6% 4 5% 3 4 6% 16%	2660
December	1st to 10th	Night	20% 26% 6% 10% 6% 4 4 3 4 3 13%	2660
	11th to 20th	Night	19% 23% 6% 13% 5% 4 3 3 4 5% 16%	3288
	21st to end	Night	26% 22% 7% 14% 6% 4 3 2 3 4 10%	5044

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	70% 6% 10% 9% 5%	2251
	11th to 20th	Day	74% 7% 7% 6% 5% 1	2662
	21st to end	Day	73% 5% 7% 8% 6%	3124
February	1st to 10th	Day	73% 4 6% 12% 4 1	1710
	11th to 20th	Day	63% 4 10% 13% 8% 1	1672
	21st to end	Day	66% 4 9% 14% 6%	1441
March	1st to 10th	Day	57% 6% 14% 13% 10%	3428
	11th to 20th	Day	60% 5% 11% 16% 7% 1	3480
	21st to end	Day	47% 5% 12% 20% 15% 2	3815
April	1st to 10th	Day	56% 5% 10% 18% 10% 1	2245
	11th to 20th	Day	52% 4 8% 23% 13% 1	2368
	21st to end	Day	52% 5% 9% 18% 13% 3	2470
May	1st to 10th	Day	48% 5% 12% 22% 12% 1	4170
	11th to 20th	Day	41% 7% 14% 26% 10% 1	4402
	21st to end	Day	41% 7% 14% 20% 16% 3	4837
June	1st to 10th	Day	46% 7% 10% 24% 12%	2675
	11th to 20th	Day	40% 8% 12% 23% 16% 1	2850
	21st to end	Day	45% 8% 14% 21% 12% 1	2850
July	1st to 10th	Day	41% 7% 16% 24% 11% 1	4686
	11th to 20th	Day	36% 7% 15% 31% 10% 1	4467
	21st to end	Day	34% 6% 12% 31% 17% 1	4455
August	1st to 10th	Day	42% 7% 15% 24% 10% 1	4091
	11th to 20th	Day	41% 8% 16% 25% 8%	4083
	21st to end	Day	34% 7% 14% 34% 10% 1	4408
September	1st to 10th	Day	41% 6% 14% 27% 11% 1	2280
	11th to 20th	Day	39% 6% 14% 28% 12% 1	2163
	21st to end	Day	50% 7% 11% 24% 9%	2056
October	1st to 10th	Day	45% 6% 13% 25% 10% 1	3160
	11th to 20th	Day	51% 6% 13% 22% 7%	3140
	21st to end	Day	58% 6% 13% 17% 5%	3413
November	1st to 10th	Day	58% 6% 15% 16% 6%	1609
	11th to 20th	Day	63% 7% 13% 11% 5% 1	1520
	21st to end	Day	71% 6% 9% 10% 3	1520
December	1st to 10th	Day	73% 5% 8% 10% 4	1520
	11th to 20th	Day	70% 5% 7% 11% 6%	1906
	21st to end	Day	77% 4 8% 9% 2	2605
January	1st to 10th	Night	78% 5% 6% 7% 4	4683
	11th to 20th	Night	72% 8% 8% 8% 4 1	4280
	21st to end	Night	70% 5% 9% 10% 6% 1	4532
February	1st to 10th	Night	67% 5% 9% 14% 4 1	2470
	11th to 20th	Night	62% 5% 10% 16% 7%	2405
	21st to end	Night	62% 5% 11% 16% 6%	2009
March	1st to 10th	Night	54% 5% 14% 16% 10% 1	3423
	11th to 20th	Night	56% 6% 14% 16% 8% 2	3480
	21st to end	Night	49% 6% 9% 22% 14% 1	3817
April	1st to 10th	Night	57% 4 8% 19% 10% 2	1934
	11th to 20th	Night	49% 5% 8% 21% 15% 2	1777
	21st to end	Night	53% 6% 8% 15% 17% 1	1710
May	1st to 10th	Night	43% 7% 12% 25% 12% 2	2790
	11th to 20th	Night	40% 7% 12% 25% 14% 1	2496
	21st to end	Night	35% 7% 13% 25% 18% 2	2739
June	1st to 10th	Night	46% 7% 9% 22% 15% 1	1500
	11th to 20th	Night	36% 6% 13% 25% 20% 1	1330
	21st to end	Night	43% 7% 14% 23% 12% 1	1330
July	1st to 10th	Night	39% 6% 14% 22% 17% 2	2175
	11th to 20th	Night	35% 6% 12% 34% 12% 1	2369
	21st to end	Night	32% 7% 10% 31% 19% 1	2855
August	1st to 10th	Night	37% 5% 16% 25% 16% 1	2814
	11th to 20th	Night	40% 6% 17% 24% 12% 1	2812
	21st to end	Night	34% 6% 12% 35% 12% 1	3215
September	1st to 10th	Night	35% 8% 16% 25% 14% 1	1900
	11th to 20th	Night	35% 8% 14% 31% 13%	2014
	21st to end	Night	44% 5% 13% 27% 11%	2123
October	1st to 10th	Night	38% 7% 11% 27% 17%	3800
	11th to 20th	Night	50% 6% 14% 23% 7%	3779
	21st to end	Night	54% 6% 16% 18% 6%	4120
November	1st to 10th	Night	56% 5% 12% 19% 7%	2673
	11th to 20th	Night	61% 7% 11% 13% 7% 1	2660
	21st to end	Night	70% 6% 11% 10% 3	2660
December	1st to 10th	Night	75% 5% 7% 9% 3	2660
	11th to 20th	Night	70% 7% 9% 10% 3	3288
	21st to end	Night	80% 4 6% 7% 2	5044

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	17% 30% 34% 13% 6%	180
	11th to 20th	Day	26% 24% 33% 11% 5%	222
	21st to end	Day	29% 16% 34% 18% 3	297
February	1st to 10th	Day	33% 26% 31% 6% 4	270
	11th to 20th	Day	25% 26% 40% 8% 1	270
	21st to end	Day	41% 24% 30% 4	225
March	1st to 10th	Day	25% 22% 33% 16% 3	453
	11th to 20th	Day	24% 22% 34% 16% 4	460
	21st to end	Day	33% 15% 31% 15% 6% 1	506
April	1st to 10th	Day	28% 21% 30% 15% 6%	460
	11th to 20th	Day	36% 17% 22% 15% 8% 2	452
	21st to end	Day	32% 15% 33% 13% 6% 2	460
May	1st to 10th	Day	26% 12% 32% 21% 7% 3	463
	11th to 20th	Day	20% 14% 32% 22% 10% 3	487
	21st to end	Day	18% 15% 31% 22% 12% 2	529
June	1st to 10th	Day	20% 15% 29% 28% 6% 1	505
	11th to 20th	Day	17% 13% 33% 24% 11% 3	680
	21st to end	Day	22% 11% 35% 22% 9% 2	680
July	1st to 10th	Day	13% 9% 35% 27% 15% 2	671
	11th to 20th	Day	16% 11% 27% 29% 12% 5%	547
	21st to end	Day	14% 9% 31% 29% 11% 6%	532
August	1st to 10th	Day	15% 8% 27% 29% 13% 7%	486
	11th to 20th	Day	15% 6% 26% 29% 14% 10%	479
	21st to end	Day	14% 10% 30% 23% 15% 6%	539
September	1st to 10th	Day	16% 10% 28% 25% 13% 7%	490
	11th to 20th	Day	13% 8% 27% 23% 20% 9%	490
	21st to end	Day	19% 13% 25% 25% 14% 3	490
October	1st to 10th	Day	25% 17% 27% 17% 11% 4	490
	11th to 20th	Day	28% 20% 31% 15% 6% 1	490
	21st to end	Day	35% 20% 28% 13% 4	536
November	1st to 10th	Day	31% 19% 33% 14% 3	224
	11th to 20th	Day	28% 23% 36% 12% 2	180
	21st to end	Day	31% 23% 36% 10% 1	180
December	1st to 10th	Day	29% 24% 32% 13% 2	180
	11th to 20th	Day	34% 29% 24% 10% 2 1	180
	21st to end	Day	36% 25% 29% 8% 3	198
January	1st to 10th	Night	30% 19% 29% 17% 5% 1	911
	11th to 20th	Night	31% 16% 31% 17% 4 1	760
	21st to end	Night	22% 12% 34% 24% 7% 1	836
February	1st to 10th	Night	23% 21% 32% 20% 3	760
	11th to 20th	Night	22% 19% 33% 21% 6%	743
	21st to end	Night	26% 21% 29% 20% 4	628
March	1st to 10th	Night	23% 18% 34% 22% 3	760
	11th to 20th	Night	22% 18% 34% 22% 5% 1	760
	21st to end	Night	21% 15% 31% 24% 8%	836
April	1st to 10th	Night	29% 13% 30% 23% 4	760
	11th to 20th	Night	26% 13% 28% 23% 9%	653
	21st to end	Night	24% 12% 29% 25% 10%	570
May	1st to 10th	Night	22% 6% 26% 33% 12% 1	546
	11th to 20th	Night	20% 9% 29% 31% 12%	374
	21st to end	Night	13% 5% 31% 36% 14%	411
June	1st to 10th	Night	17% 8% 32% 33% 10% 1	380
	11th to 20th	Night	13% 9% 26% 39% 12%	380
	21st to end	Night	18% 7% 25% 35% 14%	380
July	1st to 10th	Night	11% 6% 19% 45% 18% 1	370
	11th to 20th	Night	13% 5% 27% 34% 20% 1	368
	21st to end	Night	10% 5% 24% 37% 23% 1	538
August	1st to 10th	Night	13% 4 20% 36% 25% 3	567
	11th to 20th	Night	12% 5% 19% 37% 24% 3	564
	21st to end	Night	16% 6% 26% 29% 22% 2	679
September	1st to 10th	Night	13% 7% 28% 29% 19% 4	760
	11th to 20th	Night	14% 8% 22% 32% 21% 4	760
	21st to end	Night	21% 9% 20% 31% 18% 2	760
October	1st to 10th	Night	21% 12% 28% 24% 13% 1	760
	11th to 20th	Night	29% 16% 24% 21% 8% 1	760
	21st to end	Night	32% 18% 29% 19% 3	836
November	1st to 10th	Night	30% 14% 26% 21% 7% 1	779
	11th to 20th	Night	27% 21% 29% 17% 5%	760
	21st to end	Night	36% 14% 31% 17% 3 1	760
December	1st to 10th	Night	35% 22% 27% 13% 3 1	760
	11th to 20th	Night	29% 20% 33% 13% 4 1	760
	21st to end	Night	35% 15% 30% 18% 2	931

Page generated at 2024-11-07 06:55:46. Version ac07

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