Carter
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Carter clear sky chart from 2005-11-06 to 2024-12-24.

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% 9% 3 7% 5% 4 4 4 5% 7% 37%	101590
	Night	14% 9% 3 7% 5% 4 4 4 5% 7% 38%	98500
Transparency	Day	45% 4 10% 24% 15% 2	105320
	Night	44% 4 10% 23% 16% 3	102908
Seeing	Day	21% 12% 26% 22% 13% 6%	15015
	Night	19% 10% 25% 28% 16% 2	25112

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	15% 16% 7% 11% 5% 4 3 4 6% 7% 23%	2836
	11th to 20th	Day	15% 15% 7% 15% 7% 5% 3 3 4 4 24%	2840
	21st to end	Day	24% 18% 6% 6% 4 3 3 3 4 5% 23%	3124
February	1st to 10th	Day	18% 14% 5% 10% 5% 3 4 3 3 6% 29%	1748
	11th to 20th	Day	19% 12% 4 10% 4 4 4 3 5% 5% 30%	1848
	21st to end	Day	20% 13% 4 9% 3 3 3 4 4 6% 32%	1570
March	1st to 10th	Day	21% 15% 3 9% 4 4 5% 3 4 6% 28%	3269
	11th to 20th	Day	14% 7% 3 6% 5% 3 4 3 5% 7% 43%	3480
	21st to end	Day	18% 7% 3 6% 4 4 4 4 6% 7% 37%	3815
April	1st to 10th	Day	13% 10% 3 8% 5% 5% 4 3 5% 6% 38%	2124
	11th to 20th	Day	16% 8% 2 7% 4 4 4 3 5% 6% 42%	2361
	21st to end	Day	16% 8% 3 7% 5% 4 4 4 5% 6% 37%	2470
May	1st to 10th	Day	18% 10% 3 9% 5% 4 5% 4 6% 7% 29%	4082
	11th to 20th	Day	18% 9% 3 7% 5% 5% 4 4 5% 6% 34%	4081
	21st to end	Day	9% 6% 2 8% 5% 6% 6% 5% 7% 10% 35%	4476
June	1st to 10th	Day	11% 6% 2 7% 5% 4 6% 4 6% 8% 40%	2470
	11th to 20th	Day	9% 6% 2 7% 5% 5% 6% 4 7% 8% 41%	2470
	21st to end	Day	9% 6% 3 5% 5% 6% 6% 5% 6% 10% 40%	2470
July	1st to 10th	Day	10% 5% 2 6% 5% 5% 5% 4 7% 9% 40%	4120
	11th to 20th	Day	7% 5% 2 6% 5% 5% 6% 5% 8% 10% 41%	4120
	21st to end	Day	15% 10% 3 9% 6% 6% 6% 5% 6% 7% 27%	4466
August	1st to 10th	Day	8% 5% 3 7% 5% 5% 5% 5% 8% 10% 40%	4104
	11th to 20th	Day	9% 6% 3 7% 5% 5% 6% 5% 6% 11% 38%	4044
	21st to end	Day	5% 4 2 5% 4 4 4 4 6% 9% 55%	4352
September	1st to 10th	Day	13% 6% 2 5% 4 3 4 4 4 7% 48%	2090
	11th to 20th	Day	11% 6% 2 5% 3 4 3 4 5% 8% 49%	2090
	21st to end	Day	18% 7% 2 7% 4 4 3 3 4 6% 43%	2090
October	1st to 10th	Day	12% 4 2 5% 3 4 4 4 4 8% 50%	2062
	11th to 20th	Day	14% 6% 2 6% 4 4 3 3 4 6% 48%	1900
	21st to end	Day	18% 8% 3 6% 4 3 3 2 4 6% 42%	2062
November	1st to 10th	Day	12% 6% 2 5% 4 3 4 3 4 6% 51%	1762
	11th to 20th	Day	14% 10% 4 8% 5% 3 3 3 5% 6% 40%	1800
	21st to end	Day	16% 10% 3 7% 4 5% 4 3 4 6% 39%	1800
December	1st to 10th	Day	22% 13% 3 8% 4 4 4 4 5% 5% 28%	1800
	11th to 20th	Day	17% 13% 5% 9% 5% 4 4 4 4 5% 30%	2243
	21st to end	Day	17% 17% 4 11% 6% 5% 5% 3 4 6% 21%	3151
January	1st to 10th	Night	14% 16% 5% 12% 6% 5% 5% 4 4 5% 24%	4109
	11th to 20th	Night	19% 14% 5% 12% 5% 3 3 3 4 4 27%	4120
	21st to end	Night	21% 14% 5% 9% 6% 4 4 2 4 5% 27%	4532
February	1st to 10th	Night	19% 13% 4 9% 4 4 4 4 4 5% 30%	2428
	11th to 20th	Night	19% 11% 4 9% 5% 3 4 4 5% 5% 30%	2218
	21st to end	Night	21% 13% 4 10% 4 4 4 3 4 5% 29%	1884
March	1st to 10th	Night	21% 12% 3 7% 4 4 3 3 4 5% 33%	3583
	11th to 20th	Night	13% 8% 3 6% 4 4 4 3 5% 6% 43%	3480
	21st to end	Night	12% 8% 2 7% 5% 5% 5% 4 6% 7% 38%	3817
April	1st to 10th	Night	14% 8% 3 6% 5% 4 4 4 6% 7% 39%	2071
	11th to 20th	Night	14% 6% 2 5% 5% 4 4 4 5% 8% 41%	1768
	21st to end	Night	16% 8% 2 7% 4 5% 5% 3 5% 6% 39%	1710
May	1st to 10th	Night	19% 11% 4 8% 5% 5% 4 4 5% 7% 28%	2813
	11th to 20th	Night	20% 7% 2 5% 4 3 4 3 5% 8% 38%	2812
	21st to end	Night	8% 6% 2 7% 4 4 5% 5% 6% 9% 44%	3079
June	1st to 10th	Night	8% 5% 2 5% 5% 6% 5% 5% 7% 9% 44%	1710
	11th to 20th	Night	6% 4 2 7% 5% 4 5% 5% 7% 11% 45%	1710
	21st to end	Night	7% 5% 2 4 5% 4 5% 5% 7% 11% 45%	1710
July	1st to 10th	Night	7% 6% 2 6% 5% 5% 5% 4 7% 10% 44%	2840
	11th to 20th	Night	6% 5% 2 6% 5% 4 5% 5% 7% 9% 47%	2840
	21st to end	Night	12% 9% 4 9% 5% 5% 4 4 6% 7% 35%	3087
August	1st to 10th	Night	7% 6% 3 6% 5% 5% 6% 4 7% 9% 42%	2825
	11th to 20th	Night	9% 5% 2 7% 4 5% 5% 4 6% 8% 43%	2785
	21st to end	Night	4 2 1 4 3 4 4 4 6% 9% 58%	3301
September	1st to 10th	Night	11% 5% 2 5% 4 4 4 3 5% 8% 49%	2071
	11th to 20th	Night	10% 6% 2 5% 3 4 4 3 5% 7% 52%	2090
	21st to end	Night	13% 6% 2 5% 4 4 4 3 6% 7% 46%	2090
October	1st to 10th	Night	10% 6% 2 5% 4 3 3 4 5% 8% 53%	2117
	11th to 20th	Night	12% 7% 2 5% 4 4 4 3 4 7% 48%	2280
	21st to end	Night	17% 8% 2 6% 4 4 4 3 4 5% 44%	2534
November	1st to 10th	Night	12% 7% 2 5% 4 4 4 3 4 5% 50%	2536
	11th to 20th	Night	14% 9% 4 6% 4 4 4 4 5% 6% 41%	2600
	21st to end	Night	17% 11% 3 6% 4 3 4 3 4 6% 38%	2600
December	1st to 10th	Night	18% 13% 4 9% 5% 4 4 3 4 6% 29%	2600
	11th to 20th	Night	17% 10% 6% 10% 5% 4 4 3 5% 5% 32%	3172
	21st to end	Night	17% 16% 5% 9% 6% 6% 5% 4 5% 6% 22%	4578

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	61% 2 11% 16% 9% 1	2837
	11th to 20th	Day	66% 2 7% 20% 5% 1	2840
	21st to end	Day	65% 2 6% 21% 5% 1	3124
February	1st to 10th	Day	59% 2 8% 18% 11% 1	1748
	11th to 20th	Day	57% 3 7% 19% 12% 2	1858
	21st to end	Day	54% 2 8% 22% 11% 3	1570
March	1st to 10th	Day	58% 3 6% 21% 9% 3	3269
	11th to 20th	Day	43% 2 10% 27% 17% 2	3480
	21st to end	Day	47% 3 9% 27% 13% 1	3815
April	1st to 10th	Day	47% 3 10% 25% 13% 3	2124
	11th to 20th	Day	44% 3 9% 22% 18% 4	2361
	21st to end	Day	47% 4 10% 23% 12% 3	2470
May	1st to 10th	Day	55% 3 10% 21% 10% 1	4120
	11th to 20th	Day	51% 4 9% 23% 12% 1	4085
	21st to end	Day	42% 5% 13% 20% 16% 3	4489
June	1st to 10th	Day	40% 5% 12% 25% 17% 1	2470
	11th to 20th	Day	39% 5% 14% 23% 18% 2	2470
	21st to end	Day	39% 6% 14% 22% 15% 4	2470
July	1st to 10th	Day	39% 6% 15% 25% 15% 1	4055
	11th to 20th	Day	34% 6% 12% 33% 13% 1	4051
	21st to end	Day	54% 6% 9% 17% 11% 2	4324
August	1st to 10th	Day	35% 7% 15% 31% 11% 1	4091
	11th to 20th	Day	39% 6% 11% 31% 14%	4083
	21st to end	Day	26% 5% 15% 32% 20% 2	4351
September	1st to 10th	Day	37% 3 12% 22% 20% 6%	2090
	11th to 20th	Day	35% 3 10% 27% 23% 1	2090
	21st to end	Day	43% 3 7% 25% 21% 2	2090
October	1st to 10th	Day	24% 3 8% 27% 36% 2	3426
	11th to 20th	Day	28% 3 8% 30% 28% 3	3140
	21st to end	Day	32% 3 10% 29% 23% 3	3376
November	1st to 10th	Day	37% 2 8% 28% 21% 4	1762
	11th to 20th	Day	46% 2 7% 22% 19% 4	1800
	21st to end	Day	49% 3 9% 21% 17% 1	1800
December	1st to 10th	Day	58% 3 9% 21% 9% 1	1800
	11th to 20th	Day	57% 3 9% 17% 14% 1	2240
	21st to end	Day	64% 3 9% 17% 6% 1	3151
January	1st to 10th	Night	63% 2 8% 18% 8% 1	4109
	11th to 20th	Night	63% 2 6% 20% 8% 2	4120
	21st to end	Night	62% 2 8% 20% 8% 1	4532
February	1st to 10th	Night	57% 3 8% 21% 10% 1	2428
	11th to 20th	Night	56% 3 7% 21% 12% 1	2219
	21st to end	Night	60% 2 9% 16% 10% 3	1884
March	1st to 10th	Night	54% 3 5% 24% 13% 2	3583
	11th to 20th	Night	41% 4 8% 29% 17% 1	3480
	21st to end	Night	44% 3 9% 27% 16% 1	3817
April	1st to 10th	Night	43% 3 10% 24% 17% 2	2071
	11th to 20th	Night	41% 3 10% 22% 18% 6%	1768
	21st to end	Night	46% 4 11% 22% 15% 2	1710
May	1st to 10th	Night	56% 4 10% 19% 9% 2	2840
	11th to 20th	Night	45% 5% 13% 25% 12% 1	2813
	21st to end	Night	35% 5% 13% 26% 18% 4	3087
June	1st to 10th	Night	33% 6% 15% 25% 17% 3	1710
	11th to 20th	Night	31% 6% 16% 22% 21% 4	1710
	21st to end	Night	31% 7% 16% 26% 17% 4	1710
July	1st to 10th	Night	34% 8% 13% 24% 17% 4	2795
	11th to 20th	Night	31% 6% 14% 29% 17% 2	2786
	21st to end	Night	47% 6% 10% 21% 13% 3	2988
August	1st to 10th	Night	35% 7% 15% 29% 12% 1	2814
	11th to 20th	Night	37% 6% 11% 27% 18% 1	2812
	21st to end	Night	22% 6% 15% 32% 23% 4	3301
September	1st to 10th	Night	34% 4 12% 23% 19% 8%	2071
	11th to 20th	Night	33% 4 11% 23% 26% 4	2090
	21st to end	Night	38% 4 9% 23% 24% 2	2090
October	1st to 10th	Night	24% 3 8% 25% 37% 3	3533
	11th to 20th	Night	26% 3 8% 27% 30% 7%	3779
	21st to end	Night	31% 2 7% 25% 27% 8%	4170
November	1st to 10th	Night	38% 2 8% 25% 23% 4	2536
	11th to 20th	Night	44% 3 7% 20% 21% 5%	2600
	21st to end	Night	49% 2 9% 25% 14% 2	2600
December	1st to 10th	Night	56% 3 10% 20% 10% 1	2600
	11th to 20th	Night	55% 2 9% 23% 11% 1	3174
	21st to end	Night	64% 2 8% 17% 8%	4578

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	26% 22% 34% 13% 3 1	270
	11th to 20th	Day	37% 21% 31% 9% 1	270
	21st to end	Day	33% 26% 28% 9% 3	297
February	1st to 10th	Day	32% 21% 32% 13% 2	270
	11th to 20th	Day	41% 24% 28% 4 2 1	270
	21st to end	Day	38% 16% 38% 7%	225
March	1st to 10th	Day	34% 19% 30% 12% 4 1	354
	11th to 20th	Day	27% 21% 33% 14% 4 1	460
	21st to end	Day	32% 17% 31% 15% 5%	506
April	1st to 10th	Day	25% 19% 28% 19% 7% 1	460
	11th to 20th	Day	23% 16% 34% 17% 8% 3	452
	21st to end	Day	25% 16% 34% 18% 5% 2	460
May	1st to 10th	Day	25% 14% 32% 17% 10% 2	463
	11th to 20th	Day	22% 10% 30% 23% 10% 5%	487
	21st to end	Day	15% 8% 24% 28% 15% 9%	529
June	1st to 10th	Day	13% 7% 25% 30% 18% 7%	490
	11th to 20th	Day	11% 7% 27% 30% 16% 9%	490
	21st to end	Day	11% 6% 28% 28% 15% 11%	490
July	1st to 10th	Day	17% 5% 14% 26% 16% 23%	485
	11th to 20th	Day	8% 5% 23% 33% 19% 12%	484
	21st to end	Day	15% 3 18% 30% 22% 11%	532
August	1st to 10th	Day	12% 3 19% 29% 24% 13%	486
	11th to 20th	Day	15% 4 17% 33% 22% 9%	479
	21st to end	Day	9% 3 16% 30% 27% 15%	539
September	1st to 10th	Day	16% 3 15% 28% 27% 12%	490
	11th to 20th	Day	14% 2 14% 30% 29% 12%	490
	21st to end	Day	22% 7% 20% 25% 20% 5%	490
October	1st to 10th	Day	14% 6% 24% 29% 19% 7%	490
	11th to 20th	Day	16% 15% 29% 21% 14% 4	490
	21st to end	Day	22% 12% 31% 23% 11%	511
November	1st to 10th	Day	20% 11% 36% 23% 8% 1	300
	11th to 20th	Day	27% 17% 31% 18% 5% 2	300
	21st to end	Day	27% 16% 36% 16% 4 1	300
December	1st to 10th	Day	32% 18% 32% 13% 5%	300
	11th to 20th	Day	29% 19% 33% 14% 5% 1	300
	21st to end	Day	33% 18% 33% 13% 3 1	306
January	1st to 10th	Night	26% 18% 31% 19% 5%	760
	11th to 20th	Night	32% 17% 30% 18% 3	760
	21st to end	Night	25% 19% 34% 20% 3	836
February	1st to 10th	Night	28% 15% 33% 22% 2	760
	11th to 20th	Night	31% 19% 30% 19% 1	743
	21st to end	Night	32% 18% 30% 19% 1	628
March	1st to 10th	Night	26% 16% 30% 23% 5%	760
	11th to 20th	Night	25% 18% 30% 19% 8%	760
	21st to end	Night	21% 14% 32% 26% 6%	836
April	1st to 10th	Night	22% 12% 33% 25% 9%	741
	11th to 20th	Night	19% 10% 30% 28% 11% 1	563
	21st to end	Night	19% 8% 37% 28% 8% 1	570
May	1st to 10th	Night	21% 10% 28% 27% 13% 2	570
	11th to 20th	Night	19% 5% 24% 35% 16% 2	561
	21st to end	Night	10% 4 19% 34% 28% 5%	617
June	1st to 10th	Night	9% 3 22% 41% 22% 3	570
	11th to 20th	Night	6% 3 20% 39% 28% 5%	570
	21st to end	Night	9% 3 22% 37% 26% 4	570
July	1st to 10th	Night	12% 3 13% 31% 30% 10%	555
	11th to 20th	Night	6% 2 14% 38% 36% 4	552
	21st to end	Night	11% 3 12% 36% 31% 6%	624
August	1st to 10th	Night	9% 2 10% 37% 35% 6%	567
	11th to 20th	Night	10% 3 9% 38% 34% 6%	564
	21st to end	Night	8% 2 12% 34% 35% 9%	627
September	1st to 10th	Night	13% 2 12% 32% 34% 7%	741
	11th to 20th	Night	13% 2 13% 32% 33% 7%	760
	21st to end	Night	15% 6% 20% 30% 26% 2	760
October	1st to 10th	Night	13% 5% 18% 34% 26% 4	760
	11th to 20th	Night	16% 8% 28% 28% 17% 2	760
	21st to end	Night	21% 9% 28% 26% 14% 1	836
November	1st to 10th	Night	15% 12% 24% 31% 16% 2	780
	11th to 20th	Night	20% 15% 28% 27% 9% 1	800
	21st to end	Night	25% 14% 26% 27% 9% 1	800
December	1st to 10th	Night	29% 16% 27% 23% 4	800
	11th to 20th	Night	24% 14% 31% 24% 6% 1	800
	21st to end	Night	29% 14% 29% 24% 4	851

Page generated at 2024-12-21 03:13:52. Version ac07

Copyright © 2024 Attilla Danko.