Ore Lake Observatory
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Ore Lake Observatory clear sky chart from 2005-11-06 to 2024-11-28.

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	14% 10% 3 8% 5% 5% 5% 4 6% 7% 34%	101077
	Night	15% 11% 4 8% 5% 4 4 3 5% 6% 35%	98457
Transparency	Day	48% 5% 12% 22% 13% 1	104690
	Night	48% 4 11% 22% 13% 1	102983
Seeing	Day	18% 12% 29% 23% 14% 5%	15598
	Night	19% 10% 29% 29% 12% 1	25613

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
Month	Days in Month		Occurrence of each Forecast	Data Points
January	1st to 10th	Day	16% 21% 5% 11% 5% 4 4 3 5% 4 21%	2527
	11th to 20th	Day	16% 19% 6% 12% 7% 6% 6% 4 5% 5% 13%	2530
	21st to end	Day	28% 21% 6% 10% 5% 3 3 3 3 4 14%	3009
February	1st to 10th	Day	14% 14% 5% 13% 9% 5% 5% 3 6% 5% 21%	1710
	11th to 20th	Day	14% 14% 5% 13% 8% 4 5% 3 5% 6% 24%	1816
	21st to end	Day	15% 17% 4 11% 5% 5% 4 2 4 6% 26%	1570
March	1st to 10th	Day	17% 16% 5% 9% 5% 4 4 3 5% 5% 26%	3170
	11th to 20th	Day	13% 12% 5% 9% 5% 4 5% 4 5% 6% 33%	3480
	21st to end	Day	19% 12% 4 9% 6% 4 5% 3 4 6% 28%	3815
April	1st to 10th	Day	16% 13% 3 7% 6% 4 5% 4 5% 6% 31%	2235
	11th to 20th	Day	17% 9% 4 7% 5% 4 4 3 5% 7% 35%	2390
	21st to end	Day	17% 9% 4 8% 5% 4 4 4 4 7% 35%	2470
May	1st to 10th	Day	18% 8% 3 7% 4 5% 4 3 6% 7% 35%	4082
	11th to 20th	Day	16% 7% 3 7% 5% 4 5% 4 6% 8% 35%	4081
	21st to end	Day	10% 6% 3 7% 4 4 4 3 6% 9% 45%	4525
June	1st to 10th	Day	10% 6% 3 6% 5% 4 5% 5% 7% 8% 42%	2660
	11th to 20th	Day	10% 6% 2 7% 5% 5% 5% 4 6% 9% 41%	2660
	21st to end	Day	10% 6% 2 6% 5% 5% 6% 5% 8% 10% 38%	2660
July	1st to 10th	Day	10% 6% 2 7% 5% 5% 6% 5% 7% 10% 37%	4440
	11th to 20th	Day	8% 4 2 5% 5% 4 5% 4 6% 10% 48%	4440
	21st to end	Day	7% 5% 2 7% 6% 6% 5% 4 7% 9% 42%	4593
August	1st to 10th	Day	12% 5% 2 6% 4 5% 5% 5% 6% 9% 42%	4104
	11th to 20th	Day	11% 6% 2 6% 4 5% 5% 4 7% 9% 41%	4044
	21st to end	Day	8% 5% 2 7% 5% 5% 5% 5% 8% 9% 40%	4438
September	1st to 10th	Day	11% 6% 2 6% 5% 5% 6% 4 6% 8% 41%	2165
	11th to 20th	Day	9% 5% 2 5% 4 4 5% 4 6% 9% 47%	2090
	21st to end	Day	13% 7% 3 7% 5% 4 5% 4 6% 7% 37%	2090
October	1st to 10th	Day	13% 6% 3 7% 5% 4 5% 4 5% 6% 42%	2057
	11th to 20th	Day	18% 9% 3 8% 6% 4 4 3 5% 7% 33%	1900
	21st to end	Day	19% 11% 4 7% 5% 4 4 3 5% 7% 31%	1912
November	1st to 10th	Day	12% 10% 3 8% 4 4 5% 4 5% 7% 38%	1762
	11th to 20th	Day	15% 14% 3 9% 6% 5% 5% 3 5% 6% 29%	1800
	21st to end	Day	20% 12% 4 8% 5% 5% 5% 3 5% 6% 27%	1750
December	1st to 10th	Day	13% 17% 6% 13% 7% 4 5% 3 5% 5% 22%	1520
	11th to 20th	Day	15% 16% 6% 10% 5% 5% 5% 4 6% 6% 22%	1799
	21st to end	Day	26% 20% 8% 11% 5% 4 4 2 3 4 11%	2783
January	1st to 10th	Night	16% 16% 7% 11% 6% 5% 4 3 4 5% 24%	4428
	11th to 20th	Night	15% 16% 8% 14% 6% 6% 6% 4 5% 5% 15%	4440
	21st to end	Night	25% 17% 9% 12% 5% 3 3 3 3 4 17%	4648
February	1st to 10th	Night	17% 16% 5% 10% 6% 5% 4 3 5% 4 24%	2470
	11th to 20th	Night	14% 14% 4 10% 6% 5% 5% 3 5% 6% 28%	2247
	21st to end	Night	18% 11% 4 11% 5% 4 4 3 5% 7% 28%	1884
March	1st to 10th	Night	16% 12% 4 8% 5% 3 3 3 5% 6% 35%	3683
	11th to 20th	Night	9% 8% 3 6% 5% 4 5% 4 6% 8% 43%	3480
	21st to end	Night	17% 9% 3 9% 5% 4 4 3 4 6% 35%	3817
April	1st to 10th	Night	16% 10% 2 6% 7% 5% 3 4 5% 7% 36%	1961
	11th to 20th	Night	18% 9% 3 5% 5% 4 4 4 5% 7% 36%	1739
	21st to end	Night	17% 9% 2 6% 5% 4 5% 3 4 6% 38%	1710
May	1st to 10th	Night	16% 10% 3 7% 4 5% 4 3 5% 8% 35%	2813
	11th to 20th	Night	16% 6% 3 7% 4 4 4 3 5% 6% 42%	2812
	21st to end	Night	11% 5% 2 6% 4 4 4 3 5% 8% 47%	3028
June	1st to 10th	Night	11% 5% 2 5% 4 4 4 3 6% 8% 47%	1520
	11th to 20th	Night	10% 5% 2 5% 5% 4 4 5% 7% 8% 43%	1520
	21st to end	Night	9% 5% 3 6% 3 3 3 4 7% 9% 47%	1520
July	1st to 10th	Night	8% 4 2 5% 4 5% 5% 4 7% 10% 46%	2530
	11th to 20th	Night	8% 4 2 5% 3 3 3 4 6% 8% 55%	2530
	21st to end	Night	5% 4 2 6% 5% 5% 5% 4 7% 10% 47%	2960
August	1st to 10th	Night	11% 5% 2 6% 4 4 4 3 5% 8% 47%	2825
	11th to 20th	Night	9% 6% 2 5% 4 4 4 3 6% 7% 49%	2785
	21st to end	Night	8% 6% 2 7% 4 5% 4 4 5% 7% 48%	3214
September	1st to 10th	Night	10% 5% 2 6% 4 4 4 4 5% 6% 50%	1995
	11th to 20th	Night	9% 5% 1 4 3 3 4 3 5% 7% 54%	2090
	21st to end	Night	14% 7% 2 6% 4 5% 5% 3 6% 6% 43%	2090
October	1st to 10th	Night	12% 7% 3 6% 4 4 4 3 4 6% 47%	2123
	11th to 20th	Night	18% 9% 3 8% 5% 4 3 3 5% 6% 35%	2280
	21st to end	Night	20% 9% 3 7% 4 4 4 4 5% 6% 33%	2684
November	1st to 10th	Night	13% 9% 3 6% 4 4 4 3 4 6% 43%	2536
	11th to 20th	Night	16% 11% 3 8% 5% 5% 5% 4 6% 7% 31%	2600
	21st to end	Night	19% 15% 4 8% 5% 4 3 3 5% 6% 28%	2578
December	1st to 10th	Night	17% 16% 5% 11% 7% 5% 4 4 4 6% 21%	2660
	11th to 20th	Night	14% 15% 5% 11% 6% 5% 6% 4 6% 6% 23%	3373
	21st to end	Night	27% 23% 6% 11% 5% 4 3 3 4 4 12%	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	66% 4 11% 14% 6%	2528
	11th to 20th	Day	71% 6% 11% 9% 4	2530
	21st to end	Day	76% 3 10% 8% 3 1	3009
February	1st to 10th	Day	63% 6% 9% 14% 7%	1710
	11th to 20th	Day	62% 4 8% 17% 9% 1	1826
	21st to end	Day	60% 4 11% 16% 7% 2	1570
March	1st to 10th	Day	60% 4 11% 18% 7% 1	3170
	11th to 20th	Day	51% 4 13% 22% 8% 2	3480
	21st to end	Day	58% 4 11% 15% 10% 2	3815
April	1st to 10th	Day	53% 4 10% 19% 13%	2235
	11th to 20th	Day	49% 4 11% 21% 13% 2	2390
	21st to end	Day	49% 5% 12% 17% 14% 1	2470
May	1st to 10th	Day	47% 6% 11% 23% 12% 2	4120
	11th to 20th	Day	45% 7% 13% 24% 10% 1	4085
	21st to end	Day	37% 5% 11% 19% 23% 4	4538
June	1st to 10th	Day	38% 7% 12% 28% 14% 3	2660
	11th to 20th	Day	39% 6% 12% 24% 17% 2	2660
	21st to end	Day	39% 6% 14% 23% 16% 2	2660
July	1st to 10th	Day	42% 4 14% 21% 17% 2	4371
	11th to 20th	Day	32% 4 11% 33% 18% 2	4365
	21st to end	Day	38% 5% 14% 19% 22% 2	4447
August	1st to 10th	Day	39% 4 13% 26% 17% 1	4091
	11th to 20th	Day	39% 5% 9% 34% 12% 1	4083
	21st to end	Day	39% 4 13% 30% 13% 2	4437
September	1st to 10th	Day	40% 7% 13% 23% 15% 2	2165
	11th to 20th	Day	33% 6% 11% 33% 16% 1	2090
	21st to end	Day	43% 6% 11% 25% 15%	2090
October	1st to 10th	Day	32% 3 11% 31% 21% 1	3421
	11th to 20th	Day	41% 3 10% 26% 20%	3140
	21st to end	Day	46% 3 13% 25% 12% 2	3124
November	1st to 10th	Day	45% 6% 11% 24% 14% 1	1762
	11th to 20th	Day	56% 3 12% 20% 8% 2	1800
	21st to end	Day	58% 5% 12% 18% 7%	1750
December	1st to 10th	Day	64% 4 12% 16% 4	1520
	11th to 20th	Day	62% 4 14% 16% 4	1795
	21st to end	Day	79% 3 8% 6% 3	2783
January	1st to 10th	Night	63% 4 11% 16% 6% 1	4428
	11th to 20th	Night	69% 5% 12% 10% 5%	4440
	21st to end	Night	72% 3 10% 11% 3 1	4648
February	1st to 10th	Night	62% 5% 10% 14% 7% 1	2470
	11th to 20th	Night	57% 4 10% 18% 9% 1	2248
	21st to end	Night	56% 3 12% 18% 8% 2	1884
March	1st to 10th	Night	51% 4 12% 25% 8% 1	3683
	11th to 20th	Night	38% 5% 14% 22% 20% 1	3480
	21st to end	Night	50% 4 12% 23% 11% 1	3817
April	1st to 10th	Night	48% 4 10% 22% 14% 2	1961
	11th to 20th	Night	46% 4 11% 19% 18% 2	1739
	21st to end	Night	47% 5% 11% 19% 16% 3	1710
May	1st to 10th	Night	48% 5% 10% 22% 13% 3	2840
	11th to 20th	Night	43% 6% 10% 27% 13% 2	2813
	21st to end	Night	34% 5% 14% 21% 21% 5%	3036
June	1st to 10th	Night	35% 5% 12% 28% 18% 3	1520
	11th to 20th	Night	36% 6% 13% 26% 17% 2	1520
	21st to end	Night	33% 5% 14% 27% 20% 1	1520
July	1st to 10th	Night	34% 3 12% 30% 15% 6%	2490
	11th to 20th	Night	28% 3 13% 32% 22% 2	2482
	21st to end	Night	32% 5% 18% 19% 23% 3	2866
August	1st to 10th	Night	36% 4 13% 29% 18% 1	2814
	11th to 20th	Night	35% 4 10% 37% 12% 2	2812
	21st to end	Night	37% 4 11% 32% 15% 1	3214
September	1st to 10th	Night	33% 6% 12% 27% 19% 2	1995
	11th to 20th	Night	30% 4 10% 32% 22% 2	2090
	21st to end	Night	41% 5% 11% 29% 14% 1	2090
October	1st to 10th	Night	27% 3 9% 33% 27% 1	3539
	11th to 20th	Night	44% 2 11% 24% 19%	3779
	21st to end	Night	40% 3 10% 33% 14% 1	4422
November	1st to 10th	Night	42% 4 11% 26% 16% 1	2536
	11th to 20th	Night	53% 4 13% 20% 9% 1	2600
	21st to end	Night	58% 4 12% 19% 7%	2578
December	1st to 10th	Night	64% 5% 11% 14% 6%	2660
	11th to 20th	Night	60% 5% 13% 15% 6% 1	3375
	21st to end	Night	77% 4 10% 7% 2	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	25% 19% 34% 15% 6% 1	270
	11th to 20th	Day	27% 14% 41% 15% 1 1	270
	21st to end	Day	30% 16% 32% 15% 5% 1	297
February	1st to 10th	Day	24% 22% 35% 13% 3 1	270
	11th to 20th	Day	26% 21% 36% 14% 3	270
	21st to end	Day	28% 27% 32% 12% 1	225
March	1st to 10th	Day	26% 23% 33% 16% 2	294
	11th to 20th	Day	24% 12% 35% 22% 7%	460
	21st to end	Day	28% 15% 31% 20% 5% 1	506
April	1st to 10th	Day	21% 15% 33% 21% 8% 1	460
	11th to 20th	Day	25% 19% 31% 12% 7% 5%	452
	21st to end	Day	24% 15% 29% 19% 10% 2	460
May	1st to 10th	Day	25% 12% 31% 19% 10% 3	463
	11th to 20th	Day	19% 10% 29% 22% 13% 7%	487
	21st to end	Day	13% 9% 22% 27% 20% 9%	552
June	1st to 10th	Day	12% 7% 30% 29% 17% 4	680
	11th to 20th	Day	13% 7% 32% 26% 18% 4	680
	21st to end	Day	12% 9% 30% 28% 16% 5%	680
July	1st to 10th	Day	8% 6% 22% 28% 25% 11%	671
	11th to 20th	Day	10% 7% 28% 28% 18% 9%	668
	21st to end	Day	10% 4 23% 31% 23% 9%	607
August	1st to 10th	Day	8% 5% 20% 28% 25% 15%	486
	11th to 20th	Day	14% 4 19% 26% 26% 11%	479
	21st to end	Day	11% 4 21% 27% 24% 12%	539
September	1st to 10th	Day	13% 7% 22% 24% 23% 11%	490
	11th to 20th	Day	10% 4 17% 27% 27% 15%	490
	21st to end	Day	16% 10% 24% 22% 19% 9%	490
October	1st to 10th	Day	16% 10% 26% 25% 16% 7%	490
	11th to 20th	Day	20% 16% 29% 26% 10% 1	490
	21st to end	Day	30% 17% 31% 17% 4	361
November	1st to 10th	Day	15% 21% 34% 20% 8% 1	300
	11th to 20th	Day	22% 22% 33% 17% 6%	300
	21st to end	Day	27% 18% 38% 13% 4	280
December	1st to 10th	Day	25% 20% 32% 15% 7% 1	180
	11th to 20th	Day	24% 22% 40% 10% 4	204
	21st to end	Day	27% 24% 32% 15% 1	297
January	1st to 10th	Night	22% 15% 36% 21% 5% 1	950
	11th to 20th	Night	27% 13% 34% 21% 4 1	950
	21st to end	Night	21% 12% 35% 27% 5%	900
February	1st to 10th	Night	27% 13% 34% 24% 3	760
	11th to 20th	Night	23% 15% 35% 23% 4	743
	21st to end	Night	25% 14% 39% 20% 2	628
March	1st to 10th	Night	21% 13% 36% 24% 6%	760
	11th to 20th	Night	17% 17% 35% 24% 5% 1	760
	21st to end	Night	23% 12% 31% 26% 7% 1	836
April	1st to 10th	Night	19% 14% 36% 27% 4 1	631
	11th to 20th	Night	22% 10% 34% 25% 7% 1	563
	21st to end	Night	21% 9% 33% 28% 9%	570
May	1st to 10th	Night	20% 7% 32% 31% 9% 1	570
	11th to 20th	Night	22% 4 28% 33% 12% 1	561
	21st to end	Night	12% 5% 24% 36% 21% 2	617
June	1st to 10th	Night	12% 5% 24% 44% 14% 1	570
	11th to 20th	Night	12% 4 23% 43% 18%	570
	21st to end	Night	10% 4 21% 44% 20% 1	570
July	1st to 10th	Night	8% 3 16% 41% 28% 4	555
	11th to 20th	Night	10% 3 18% 39% 25% 4	552
	21st to end	Night	5% 1 19% 48% 25% 1	624
August	1st to 10th	Night	9% 1 16% 42% 29% 2	567
	11th to 20th	Night	10% 2 19% 37% 28% 4	564
	21st to end	Night	9% 2 17% 39% 30% 3	627
September	1st to 10th	Night	12% 5% 20% 33% 26% 4	665
	11th to 20th	Night	11% 3 18% 32% 31% 4	760
	21st to end	Night	15% 7% 21% 31% 21% 4	760
October	1st to 10th	Night	16% 6% 29% 30% 16% 3	760
	11th to 20th	Night	23% 12% 29% 26% 9% 1	760
	21st to end	Night	25% 12% 32% 25% 6%	836
November	1st to 10th	Night	19% 11% 31% 27% 11% 1	780
	11th to 20th	Night	22% 16% 34% 20% 7% 1	800
	21st to end	Night	26% 13% 34% 22% 5%	789
December	1st to 10th	Night	24% 16% 34% 20% 6%	760
	11th to 20th	Night	24% 13% 38% 22% 3	900
	21st to end	Night	33% 12% 34% 19% 2	1045

Page generated at 2024-11-25 00:22:18. Version ac07

Copyright © 2024 Attilla Danko.