Phenix City
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Phenix City clear sky chart from 2005-11-06 to 2024-02-20.

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	12% 5% 2 5% 5% 3 5% 5% 6% 8% 43%	78848
	Night	12% 6% 2 5% 5% 3 4 5% 5% 8% 45%	80345
Transparency	Day	38% 8% 12% 18% 18% 6%	78571
	Night	36% 8% 11% 18% 20% 8%	80141
Seeing	Day	14% 8% 21% 24% 21% 11%	13823
	Night	14% 6% 22% 31% 23% 4	23930

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% 8% 3 6% 5% 3 3 4 5% 7% 41%	2836
	11th to 20th	Day	12% 5% 2 4 4 2 3 3 4 7% 54%	2840
	21st to end	Day	22% 8% 3 5% 4 2 3 3 4 6% 40%	3444
February	1st to 10th	Day	15% 8% 3 6% 6% 3 5% 5% 5% 6% 39%	1900
	11th to 20th	Day	19% 7% 3 5% 3 2 4 4 5% 5% 43%	1838
	21st to end	Day	15% 7% 3 5% 6% 4 5% 5% 5% 6% 39%	1480
March	1st to 10th	Day	13% 6% 2 5% 4 3 4 4 4 4 50%	1820
	11th to 20th	Day	15% 7% 3 5% 4 3 5% 5% 6% 6% 41%	1980
	21st to end	Day	13% 5% 2 5% 5% 3 5% 5% 5% 7% 44%	2178
April	1st to 10th	Day	11% 4 4 5% 5% 3 5% 4 5% 8% 46%	2075
	11th to 20th	Day	12% 5% 2 4 4 3 4 5% 5% 8% 48%	2134
	21st to end	Day	7% 3 2 5% 5% 3 4 5% 5% 7% 54%	2219
May	1st to 10th	Day	9% 4 2 4 3 3 4 5% 5% 8% 53%	2340
	11th to 20th	Day	8% 5% 2 5% 5% 3 5% 6% 6% 10% 44%	2301
	21st to end	Day	9% 5% 2 4 5% 4 5% 5% 8% 10% 43%	2531
June	1st to 10th	Day	10% 5% 3 6% 7% 3 7% 7% 8% 12% 31%	2340
	11th to 20th	Day	7% 3 2 5% 6% 4 6% 7% 8% 12% 41%	2340
	21st to end	Day	6% 5% 2 6% 6% 4 8% 7% 8% 12% 35%	2340
July	1st to 10th	Day	9% 5% 3 6% 7% 5% 7% 8% 9% 11% 29%	2340
	11th to 20th	Day	8% 6% 3 6% 7% 5% 7% 8% 8% 12% 31%	2340
	21st to end	Day	7% 5% 3 7% 6% 4 7% 8% 9% 13% 32%	2547
August	1st to 10th	Day	8% 5% 3 6% 6% 4 7% 8% 10% 12% 32%	2225
	11th to 20th	Day	11% 5% 2 6% 7% 5% 8% 7% 8% 10% 30%	2125
	21st to end	Day	12% 6% 3 6% 7% 3 7% 7% 8% 10% 31%	2376
September	1st to 10th	Day	9% 5% 2 6% 7% 4 6% 7% 6% 8% 39%	2010
	11th to 20th	Day	14% 5% 2 6% 5% 3 5% 6% 6% 8% 40%	1980
	21st to end	Day	11% 5% 2 6% 6% 4 4 4 5% 6% 48%	1980
October	1st to 10th	Day	11% 5% 2 5% 3 2 3 3 5% 7% 53%	1980
	11th to 20th	Day	11% 3 2 3 3 3 3 4 5% 8% 55%	1947
	21st to end	Day	10% 6% 2 5% 4 2 3 3 4 5% 56%	1980
November	1st to 10th	Day	11% 5% 2 5% 4 2 3 5% 4 5% 55%	1675
	11th to 20th	Day	13% 5% 2 4 3 2 3 4 3 6% 56%	1710
	21st to end	Day	14% 5% 2 5% 4 3 5% 5% 4 8% 47%	1710
December	1st to 10th	Day	15% 6% 3 5% 5% 3 5% 4 6% 6% 43%	1710
	11th to 20th	Day	16% 9% 3 6% 5% 2 3 4 4 5% 44%	2153
	21st to end	Day	20% 8% 3 5% 4 2 4 3 4 6% 40%	3124
January	1st to 10th	Night	17% 7% 3 5% 4 3 4 5% 5% 7% 40%	4109
	11th to 20th	Night	11% 6% 2 5% 5% 2 4 5% 5% 8% 48%	4120
	21st to end	Night	21% 10% 3 5% 4 2 3 3 3 5% 41%	4208
February	1st to 10th	Night	15% 6% 3 6% 6% 3 4 3 5% 6% 44%	2280
	11th to 20th	Night	20% 6% 2 5% 3 2 4 4 4 5% 46%	2213
	21st to end	Night	16% 6% 2 5% 5% 3 4 4 5% 6% 43%	1776
March	1st to 10th	Night	10% 5% 2 5% 5% 3 3 4 5% 7% 51%	2139
	11th to 20th	Night	13% 6% 2 5% 6% 2 4 5% 6% 8% 43%	1980
	21st to end	Night	12% 4 3 5% 5% 2 4 4 5% 7% 48%	2178
April	1st to 10th	Night	10% 5% 2 4 5% 3 5% 5% 6% 7% 48%	1899
	11th to 20th	Night	13% 4 3 4 4 2 3 4 5% 9% 50%	1775
	21st to end	Night	7% 4 1 4 4 3 4 4 5% 8% 57%	1738
May	1st to 10th	Night	7% 4 2 4 4 3 4 5% 5% 8% 55%	1620
	11th to 20th	Night	8% 6% 2 5% 5% 4 5% 6% 7% 8% 45%	1592
	21st to end	Night	8% 3 1 5% 6% 3 5% 6% 6% 10% 46%	1744
June	1st to 10th	Night	8% 6% 2 6% 6% 5% 7% 7% 9% 8% 34%	1620
	11th to 20th	Night	3 3 3 3 5% 4 5% 7% 8% 13% 46%	1620
	21st to end	Night	5% 5% 3 5% 6% 4 6% 7% 10% 13% 36%	1620
July	1st to 10th	Night	6% 4 3 5% 7% 4 7% 8% 10% 14% 32%	1620
	11th to 20th	Night	5% 4 2 6% 6% 4 7% 8% 9% 13% 35%	1620
	21st to end	Night	6% 3 2 5% 6% 3 6% 7% 9% 15% 38%	1771
August	1st to 10th	Night	6% 5% 3 6% 7% 4 7% 7% 7% 14% 35%	1708
	11th to 20th	Night	7% 5% 2 4 7% 4 6% 7% 9% 12% 36%	1776
	21st to end	Night	11% 7% 3 7% 5% 4 5% 6% 7% 9% 36%	1980
September	1st to 10th	Night	9% 5% 2 5% 6% 4 5% 6% 7% 11% 40%	1930
	11th to 20th	Night	11% 7% 3 5% 5% 4 5% 5% 6% 7% 42%	1980
	21st to end	Night	8% 5% 2 6% 6% 4 5% 4 5% 7% 48%	1980
October	1st to 10th	Night	9% 4 2 5% 3 2 4 4 4 7% 56%	1980
	11th to 20th	Night	10% 4 2 3 3 2 3 4 4 6% 57%	2011
	21st to end	Night	11% 5% 1 4 4 2 3 4 4 5% 57%	2376
November	1st to 10th	Night	10% 4 2 5% 4 2 3 4 4 5% 59%	2398
	11th to 20th	Night	13% 4 2 3 4 2 3 3 4 5% 57%	2470
	21st to end	Night	14% 6% 2 4 4 3 4 4 4 7% 49%	2470
December	1st to 10th	Night	15% 7% 2 5% 4 3 4 4 5% 6% 45%	2470
	11th to 20th	Night	17% 6% 2 5% 5% 2 4 3 4 6% 47%	3042
	21st to end	Night	20% 7% 2 6% 5% 3 4 4 5% 6% 36%	4532

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	41% 6% 6% 17% 23% 7%	2837
	11th to 20th	Day	31% 4 6% 20% 29% 10%	2840
	21st to end	Day	47% 5% 6% 13% 20% 10%	3444
February	1st to 10th	Day	46% 5% 7% 16% 19% 8%	1900
	11th to 20th	Day	44% 5% 5% 16% 22% 8%	1848
	21st to end	Day	44% 7% 7% 14% 19% 9%	1480
March	1st to 10th	Day	37% 5% 7% 17% 22% 11%	1820
	11th to 20th	Day	43% 7% 10% 15% 17% 9%	1980
	21st to end	Day	38% 7% 11% 18% 21% 5%	2178
April	1st to 10th	Day	37% 6% 10% 22% 16% 9%	2075
	11th to 20th	Day	35% 5% 10% 19% 23% 9%	2134
	21st to end	Day	28% 7% 9% 23% 27% 5%	2219
May	1st to 10th	Day	29% 7% 11% 22% 26% 6%	2340
	11th to 20th	Day	34% 10% 15% 22% 16% 3	2305
	21st to end	Day	33% 10% 13% 23% 19% 3	2531
June	1st to 10th	Day	41% 13% 16% 18% 10% 2	2340
	11th to 20th	Day	32% 12% 19% 24% 12% 2	2340
	21st to end	Day	37% 14% 19% 18% 9% 2	2340
July	1st to 10th	Day	41% 15% 24% 13% 6% 2	2275
	11th to 20th	Day	41% 16% 20% 15% 7% 1	2271
	21st to end	Day	38% 15% 23% 18% 7%	2405
August	1st to 10th	Day	38% 16% 22% 20% 4	2212
	11th to 20th	Day	45% 13% 18% 15% 8% 2	2125
	21st to end	Day	44% 12% 18% 15% 9% 2	2376
September	1st to 10th	Day	41% 11% 14% 15% 15% 4	2010
	11th to 20th	Day	40% 9% 13% 16% 17% 5%	1980
	21st to end	Day	36% 6% 8% 21% 21% 7%	1980
October	1st to 10th	Day	31% 5% 11% 19% 24% 9%	1980
	11th to 20th	Day	28% 6% 8% 22% 27% 10%	1947
	21st to end	Day	31% 4 6% 14% 31% 14%	1980
November	1st to 10th	Day	32% 5% 6% 14% 28% 15%	1675
	11th to 20th	Day	31% 3 7% 17% 26% 15%	1710
	21st to end	Day	37% 6% 7% 17% 23% 10%	1710
December	1st to 10th	Day	41% 6% 10% 16% 20% 7%	1710
	11th to 20th	Day	44% 4 6% 14% 24% 8%	2150
	21st to end	Day	45% 6% 7% 17% 22% 4	3124
January	1st to 10th	Night	42% 7% 6% 14% 23% 8%	4109
	11th to 20th	Night	33% 5% 8% 21% 23% 10%	4120
	21st to end	Night	48% 4 4 12% 24% 9%	4208
February	1st to 10th	Night	42% 4 7% 17% 18% 12%	2280
	11th to 20th	Night	41% 5% 6% 14% 22% 12%	2214
	21st to end	Night	41% 7% 9% 15% 15% 13%	1776
March	1st to 10th	Night	33% 6% 8% 18% 22% 13%	2139
	11th to 20th	Night	39% 8% 11% 14% 19% 9%	1980
	21st to end	Night	34% 7% 10% 20% 23% 7%	2178
April	1st to 10th	Night	35% 7% 12% 16% 20% 11%	1899
	11th to 20th	Night	32% 5% 7% 22% 24% 10%	1775
	21st to end	Night	27% 5% 11% 24% 25% 9%	1738
May	1st to 10th	Night	27% 8% 11% 21% 26% 7%	1620
	11th to 20th	Night	35% 10% 16% 18% 16% 5%	1593
	21st to end	Night	31% 9% 13% 22% 19% 5%	1745
June	1st to 10th	Night	40% 12% 17% 17% 13% 1	1620
	11th to 20th	Night	25% 12% 21% 27% 13% 2	1620
	21st to end	Night	33% 15% 19% 19% 11% 3	1620
July	1st to 10th	Night	35% 19% 22% 15% 7% 2	1575
	11th to 20th	Night	36% 16% 24% 17% 7% 1	1566
	21st to end	Night	29% 14% 27% 22% 8% 1	1672
August	1st to 10th	Night	35% 16% 21% 23% 5%	1697
	11th to 20th	Night	35% 15% 22% 17% 9% 2	1776
	21st to end	Night	42% 11% 18% 15% 11% 3	1980
September	1st to 10th	Night	36% 10% 16% 18% 15% 5%	1930
	11th to 20th	Night	37% 10% 12% 18% 17% 6%	1980
	21st to end	Night	35% 8% 9% 19% 22% 8%	1980
October	1st to 10th	Night	28% 6% 11% 21% 22% 12%	1980
	11th to 20th	Night	28% 5% 8% 18% 29% 11%	2011
	21st to end	Night	30% 4 6% 15% 29% 17%	2376
November	1st to 10th	Night	29% 4 9% 16% 26% 16%	2398
	11th to 20th	Night	32% 3 6% 16% 27% 16%	2470
	21st to end	Night	37% 5% 8% 16% 24% 10%	2470
December	1st to 10th	Night	39% 6% 10% 17% 22% 6%	2470
	11th to 20th	Night	39% 4 7% 14% 28% 8%	3044
	21st to end	Night	46% 6% 7% 19% 18% 4	4532

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	21% 20% 37% 17% 5%	270
	11th to 20th	Day	17% 24% 31% 18% 7% 2	270
	21st to end	Day	21% 24% 40% 11% 3 1	297
February	1st to 10th	Day	22% 22% 34% 16% 6%	270
	11th to 20th	Day	28% 18% 36% 16% 3	267
	21st to end	Day	17% 23% 40% 18% 1	198
March	1st to 10th	Day	20% 16% 37% 19% 6% 2	260
	11th to 20th	Day	19% 15% 35% 22% 8% 1	420
	21st to end	Day	16% 14% 35% 25% 8% 1	462
April	1st to 10th	Day	16% 16% 27% 27% 12% 2	420
	11th to 20th	Day	14% 13% 30% 23% 17% 3	412
	21st to end	Day	10% 10% 24% 33% 20% 3	420
May	1st to 10th	Day	10% 8% 26% 30% 22% 5%	423
	11th to 20th	Day	10% 2 20% 30% 27% 11%	447
	21st to end	Day	13% 3 13% 28% 29% 14%	485
June	1st to 10th	Day	12% 2 12% 31% 28% 15%	450
	11th to 20th	Day	7% 2 12% 23% 28% 28%	450
	21st to end	Day	6% 3 15% 25% 27% 24%	450
July	1st to 10th	Day	8% 2 5% 22% 36% 28%	445
	11th to 20th	Day	5% 1 5% 20% 34% 36%	444
	21st to end	Day	6% 1 7% 18% 40% 29%	488
August	1st to 10th	Day	11% 1 7% 22% 31% 27%	446
	11th to 20th	Day	9% 2 6% 18% 38% 27%	439
	21st to end	Day	14% 2 6% 26% 32% 21%	495
September	1st to 10th	Day	9% 3 10% 24% 38% 17%	450
	11th to 20th	Day	16% 2 10% 27% 32% 13%	450
	21st to end	Day	11% 2 12% 29% 34% 12%	450
October	1st to 10th	Day	14% 4 24% 31% 20% 8%	450
	11th to 20th	Day	10% 7% 19% 33% 24% 7%	450
	21st to end	Day	16% 8% 24% 27% 21% 4	495
November	1st to 10th	Day	19% 8% 23% 30% 15% 4	273
	11th to 20th	Day	15% 11% 37% 25% 10% 1	270
	21st to end	Day	13% 14% 33% 27% 12% 1	270
December	1st to 10th	Day	21% 14% 36% 21% 7% 1	270
	11th to 20th	Day	28% 14% 31% 22% 4 1	270
	21st to end	Day	26% 12% 29% 26% 6%	297
January	1st to 10th	Night	19% 13% 34% 27% 6%	760
	11th to 20th	Night	18% 11% 31% 31% 9%	760
	21st to end	Night	20% 11% 36% 28% 4	836
February	1st to 10th	Night	18% 10% 31% 35% 6%	760
	11th to 20th	Night	23% 8% 35% 30% 5%	742
	21st to end	Night	18% 11% 38% 29% 5%	592
March	1st to 10th	Night	12% 12% 34% 36% 7%	720
	11th to 20th	Night	17% 9% 34% 28% 12% 1	720
	21st to end	Night	13% 11% 31% 32% 12%	792
April	1st to 10th	Night	13% 7% 30% 34% 16%	639
	11th to 20th	Night	15% 9% 25% 32% 19% 1	533
	21st to end	Night	9% 4 25% 36% 26% 1	540
May	1st to 10th	Night	8% 5% 24% 35% 26% 3	540
	11th to 20th	Night	11% 2 19% 33% 29% 5%	531
	21st to end	Night	10% 1 10% 32% 40% 6%	584
June	1st to 10th	Night	9% 2 10% 37% 36% 6%	540
	11th to 20th	Night	4 3 8% 29% 42% 15%	540
	21st to end	Night	6% 2 6% 28% 48% 10%	540
July	1st to 10th	Night	8% 1 3 26% 47% 15%	525
	11th to 20th	Night	6% 1 2 19% 50% 20%	522
	21st to end	Night	6% 1 5% 24% 51% 14%	591
August	1st to 10th	Night	7% 1 5% 24% 43% 19%	537
	11th to 20th	Night	10% 1 6% 23% 49% 11%	534
	21st to end	Night	13% 2 8% 26% 37% 14%	594
September	1st to 10th	Night	11% 2 7% 24% 44% 12%	670
	11th to 20th	Night	13% 2 13% 33% 35% 5%	720
	21st to end	Night	10% 2 14% 32% 39% 3	720
October	1st to 10th	Night	10% 3 21% 36% 26% 5%	720
	11th to 20th	Night	13% 4 20% 34% 26% 3	720
	21st to end	Night	13% 4 24% 34% 22% 2	792
November	1st to 10th	Night	12% 5% 21% 38% 22% 2	740
	11th to 20th	Night	14% 8% 30% 33% 14% 1	760
	21st to end	Night	16% 7% 28% 34% 13% 2	760
December	1st to 10th	Night	20% 8% 27% 33% 11% 1	760
	11th to 20th	Night	21% 7% 31% 30% 10% 1	760
	21st to end	Night	27% 9% 25% 31% 8%	836

Page generated at 2024-02-17 05:28:36. Version ac07

Copyright 2024 Attilla Danko