ARCUS Sea Ice August forecast online

SEARCH : Study of Environmental Arctic Change

The August SEARCH forecast is now online, a little late this month. As before, I’ll make the poll for WUWT readers available at the end of the month for the final forecast. Personally I think the last WUWT reader poll results ran a bit high, but we didn’t submit the highest forecasts by any measure.

From: ARCUS.org:

Many thanks to all contributors to the August Sea Ice Outlook. We received 21 responses for the Pan-Arctic report (Figure 1), with estimates in the range of just below 4.0 million square kilometers to as high as 5.4 million square kilometers for the September arctic mean sea ice extent. As in the July Outlook, the median value was 4.6 million square kilometers with quartile values of 4.3 and 4.6 million square kilometers, a rather narrow range. All contributions are well below the 1979-2007 climatological mean of 6.7 million square kilometers, and also below all values seen prior to 2007. Thus, the low values observed the last four summers are expected to continue again this September. On a regional level, the long-term downward trend is expected to continue in all regions except the Greenland Sea.

July 2011 set a new record low for the month during the satellite data record despite a significant slowing down of ice loss during the latter half of the month as weather changed to cooler conditions. In August, warmer conditions returned, which combined with a rather diffuse ice cover in the Beaufort and Chukchi seas, has led to a speed-up in the rate of ice loss at the beginning of August, particularly in the Chukchi Sea. Whether or not this rate of ice loss will continue will depend on what the weather does over the next few weeks. However, with approximately a month left in the melt season, it is very unlikely that the September minimum will end up above 5 million square kilometers.

Credit: Arctic Research Consortium of the U.S. (ARCUS).

Figure 1. Distribution of individual Pan-Arctic Outlook (August Report) values for September 2010 sea ice extent. Credit: Arctic Research Consortium of the U.S. (ARCUS). Click to enlarge.

Download High Resolution Version of Figure 1.

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44 thoughts on “ARCUS Sea Ice August forecast online

  1. As I posted in tips earlier, the DMI graph of mean temperature above 80°N shown on the ice reference page appears to show mean temps have dropped below freezing. The temperature is also noticeably lower than the ERA40 average. What this proves I have no idea, but I thought it was interesting.

  2. Put me down for 5 million also … a guesstimate but one that makes sense to me given arctic temperatures and winds.

  3. Interresting that the other two “public outlook” forcasts are labeled as “statistical”, while ours is labeled as “huristic”, as is the Canadian Ice Service. The color coding system/labels don’t seem very informative to me.

  4. My first guesstimate was 5 M sq.Km (same as Canadian Ice Service predicted), but I’ve since downgraded that to 4.5 M sq. Km. I’d REALLY like to see some discussion of the other factors driving Arctic ice loss (wind, currents, even icebreaker & freighter traffic) vs. just AGW forcings.

    Great post and discussion, this is why I like WUWT….we address science that nobody else seems to want to discuss.

  5. It’s not going to be long until it’s gone folks. The future looks dim. Even The Weather Channel was talking about how parts of Fl could be under water by 2100. I feel for future generations.

  6. I have been following the Raw Data from here:
    ftp://sidads.colorado.edu/DATASETS/NOAA/
    particularly the GO2186 Directory link on that page, and came up with this:

    Pencil in your own continuation curve to Sept. 21. I come up with 4.7 to 5.0 M Km Sq.
    What do you estimate based on the curve extension of the Raw Data?

  7. Brian says:
    August 17, 2011 at 11:25 am
    It’s not going to be long until it’s gone folks. The future looks dim. Even The Weather Channel was talking about how parts of Fl could be under water by 2100. I feel for future generations.
    —–
    CRS reply Brian, you sound just like I did back in 1979, when I started studying AGW in earnest.

    We don’t know nearly enough to say, definitively, why some of these natural phenomena are occurring. The quick & easy thing, as always, is “blame mankind.” However, there are clearly some natural factors in play which have been understudied by the scientific community.

    Don’t worry about the future generations. I used to worry about what life would be like in 2000, and it’s pretty good actually. We can cure many more diseases, life expectancy and quality of life is improving, the environment is FAR better than in the 1970’s (except in China), and science continues to deliver great discoveries.

  8. This is a table of the June, July, August estimates combined.
    I show the means and the Low = Mean – uncert.
    If No uncertainty was specified, I assumed +/- 0.1.
    They are arranged with earliest predictions first.


    __________________Mean________________Low (min var 0.1)____
    __________________Jun__Jul__Aug______Jun__Jul__Aug
    --- Unchanged since June
    Peterson et Al____4.0__4.0__4.0______2.8__2.8__2.8
    Hamilton__________4.4__4.4__4.4______3.5__3.5__3.5
    Stroeve et al_____4.7__4.7__4.7______4.6__4.6__4.6
    Morison and Unt.__4.8__4.8__4.8______4.7__4.7__4.7
    Anderson__________4.1_______4.1______4.0_______4.0
    Grumbine__________4.4________________3.9__________
    Tivy______________4.5________________3.9__________
    Wang______________5.0________________4.5__________
    Egan______________5.6________________5.5__________
    ---June, July, Aug revisions
    Lindsay and Zhan__4.9__4.1__4.1______4.5__3.7__3.7
    Folkerts__________4.7__4.2__4.2______4.5__4.0__4.0
    Lukovich et al____4.6__4.6__4.5______4.5__4.5__4.4
    arbetter et al____4.4__4.3__4.5______4.3__4.2__4.4
    Beitsch et al_____4.8__4.7__4.6______3.1__4.2__4.3
    Zhang_____________4.1__4.3__4.6______3.5__3.8__4.0
    WUWT______________5.5__5.1__5.0______5.1__4.7__4.6
    Kauker et al______5.4__5.5__5.2______4.8__5.0__5.1
    Canadian Ice Ser__5.0__4.7__4.7______4.9__4.5__4.5
    Wadhams___________4.1_______4.0______4.0_______3.9
    --- July, Aug
    Randles________________4.4__4.3___________4.3__3.5
    Meier et al____________4.7__4.5___________4.1__4.1
    Blanchard-Wigg.________4.6__4.6___________4.1__4.1
    --- July, Aug, only
    Liljergren__________________4.6________________3.7
    Wu et al____________________4.6________________4.4
    Shibata et al_______________5.4________________5.3

  9. Steven Rasey,

    You left out the world’s most renowned Arctic ice specialist… R. Gates!
    [Do I have to write: /sarc?]

    Anyway, there’s an interesting article here about old driftwood being exposed as the ice recedes.

  10. Bloke down the pub says:
    August 17, 2011 at 10:46 am

    As I posted in tips earlier, the DMI graph of mean temperature above 80°N shown on the ice reference page appears to show mean temps have dropped below freezing. The temperature is also noticeably lower than the ERA40 average. What this proves I have no idea, but I thought it was interesting.
    =======================================================

    Well, it shows a couple of things we should note.

    First and foremost, arctic temps have very little to do with ice loss.

    Secondly, there is another issue that we can see…… noting the graph of DMI, we see this is in conflict with GISS’ estimation of arctic temps….. go here, http://data.giss.nasa.gov/gistemp/maps/ and play with the app. Here is a map of Jun’s temps….. http://suyts.files.wordpress.com/2011/08/image_thumb2.png?w=646&h=381 You can play with the app to get July’s. (Be sure to change the base period to match DMI’s, 1958-2002 for a true comparison) Compare to http://ocean.dmi.dk/arctic/meant80n.uk.php

    I think we can tell Hansen to put away his pink and red crayons.

  11. I have become a little confused. the ARCUS Sea Ice survey is for the forecast of a measure best represented by which chart on the WUWT Sea Ice Page?
    The first one? IARC-JAXA AMSR-E Sea Ice Area (>15%)?

  12. I’ve been saying 4.6 since May (under the rationale of the 2010 El Nino) and now my bet is in the middle of the spread. It’s going to be interesting, and I’d love to be wrong and find it’s 5.0.

    Rich.

  13. Meanwhile on the weather front, New Zealand continues to shiver on one of the coldest spells they can remember. Funny how the LW papers have been emphasising what a rare event this is and it has been given the pseudonym of a ‘Polar Blast’. Only thing missing is “from the past” and they haven’t been quite game enough yet to blame it on global warming BUT it is an “extreme event”. Wonder what the tack will be if it happens next year?

    http://news.smh.com.au/breaking-news-world/new-zealand-shivers-through-big-chill-20110815-1iu3w.html

  14. King of Cool says:
    August 17, 2011 at 2:25 pm

    ……Only thing missing is “from the past” and they haven’t been quite game enough yet to blame it on global warming BUT it is an “extreme event”. Wonder what the tack will be if it happens next year?
    =================================================================
    It will be that they had said all along this would happen….. that hotter weather causes more precipitation and extreme events….. (all the while never addressing the record cold temps occurring) and ignoring the fact they said global warming caused the milder winters just prior to the last two we experienced.

    Is what happened here in the States anyway……. look for further advancement of the warmcold theory combined with the drywet principle.

  15. I wonder where the whole 5.5+ crew went to.

    4.8. no change from the original prediction. But the right weather and currents.. 4.3. Slush puppy ice. so maybe lucia’s 4.6 .A better thing to look at is the volume.

    Nevens place is nice if you want to learn something

  16. Brian says:
    August 17, 2011 at 11:25 am

    It’s not going to be long until it’s gone folks. The future looks dim. Even The Weather Channel was talking about how parts of Fl could be under water by 2100. I feel for future generations.

    Why?

    You could lose every square KM of the 4.5 million km of today’s Arctic ice cap – that is, you could drop the September minimum to zero – and not affect the heat absorbed at all. (You would increase the heat LOST by the Arctic waters to evaporation and radiation to space, so temperatures the following autumn would continue decreasing – as they are now and have been every summer ever since 1958 – so global temperatures would decline with increased ice lost.)

    Why?

    A 4.0 million km^2 Arctic minimum ice extent can be closely approximated as a cap on the globe between latitude 79.2 degrees and the pole (90 north). At minimum ice extent in September, less than 15% of inbound radiation is absorbed – the rest is reflected at these low incidence angles from BOTH ice and open water just about equally. Albedo (color of the ice or water) is irrelevant: BOTH reflect equally the radiation at the actual angles found in the Arctic where the ice is found.

    All those thousands of scare CAGW stories about Arctic sea-ice-albedo feedback heating the world? Propaganda. Nothing more than propaganda.

  17. DMI shows below freezing and measurements linked represents increasing number below zero too.

    We are almost around the time of year when the Arctic circle above 80N remains below freezing and will continue to decline over the weeks. As we know ice loss still continues, ocean SST’s and currents play a bigger role than atmospheric temperatures.

  18. RACookPE1978 says:
    August 17, 2011 at 4:03 pm

    It seems counterintuitive, but loss of Arctic Sea Ice might be the 1st stages of a cooling planet. It’s the landmasses of the Temperate Zones that will feel the pain. The Oceans will just have an easier time of it passing warmer waters into the Arctic where the heat energy will be Lost in Space.

  19. BTW – mean temperature above 80 Deg N is now below freezing. Just a tad earlier than normal.

  20. rbateman says:
    August 17, 2011 at 8:49 pm

    It seems counterintuitive, but loss of Arctic Sea Ice might be the 1st stages of a cooling planet. It’s the landmasses of the Temperate Zones that will feel the pain. The Oceans will just have an easier time of it passing warmer waters into the Arctic where the heat energy will be Lost in Space.

    _____________________________________________________________________________

    That’s my thinking too. Very cold air flowing over cold, but ice-free water, is the perfect recipe for heavy snowfall as anyone who lives near the Great Lakes will readily testify.

    Were that to happen on an oceanic scale, you have a moisture source with the potential to build ice sheets on the surrounding land masses………

  21. From steven mosher on August 17, 2011 at 3:51 pm:

    Nevens place is nice if you want to learn something

    Yeah, like something about those idiot (C)AGW-deniers who refuse to accept the peer-reviewed consensus view of Climate Science™ who gather over at that moron Watts’ WUWT site. How can so much scientific illiteracy and outright stupidity be so concentrated at one location?

    After hanging around there for awhile, I’d be equally served by studying race relations at a New Black Panthers meeting. I want to know how their membership feels about the decimation of the black middle class under Obama’s policies and how blacks were doing better during George W. Bush’s administration. I’m certain my questions will be as warmly received there as my questions on climate science will be over at Neven’s.

    I’ve had a few concussions in my life thus have probably have some brain damage, but not enough to make hanging around Neven’s seem a worthy use of my time. I’ll take a pass on that, but you go right ahead Mosh and enjoy yourself over there. ☺

  22. Slightly off topic , but with regard to what is happening in the Arctic this posting from our happy band of Old Pulteny oarsmen says more than all the models produced this week.

    We have been extremely lucky with the amount of wildlife sightings, which have included polar bears, numerous walrus, seals and Beluga whales. All this is evidence of the incredible bio-productivity at this time of year. The water is alive with plankton and shrimp that have multiplied rapidly due to the 24-hour sunlight. Now the thick blanket of ice has been removed for the summer these organisms can flourish for a brief few months before the ice returns. These organisms are supporting the fascinating larger mammals all the way up the food chain. Being able to witness such incredible wildlife untouched by Man in its natural environment is a truly awesome experience.”

  23. RACookPE1978 says:
    August 17, 2011 at 4:03 pm
    ———–
    BOTH reflect equally the radiation at the actual angles found in the Arctic where the ice is found.
    ————
    This claim seems to be based on the “sea is perfectly flat” theory. I prefer the “sea has waves” theory.

  24. James Sexton says
    ———–
    First and foremost, arctic temps have very little to do with ice loss.
    ———–
    So this appears to be based on the “ice doesn’t melt when it gets warmer” theory.

    James are you going to impress us with a graph showing a decades long increasing trend trend in Arctic wind intensity?

    And a corresponding increase in the amount of ice floating around the Atlantic. And proof that the incease amount corresponds exactly to ice loss.

    Or is this just a gut feeling you have?

  25. Melt ponds that are deep enough to be counted as real melt, when these start to freeze over as the mean temps drop below 0c we may see an early bottoming out of the ice minimum followed by a speedy rise. Fresh water melt ponds will freeze faster than open ocean, it remains to be seen what proportion of the remaining polar sea ice is melt ponds and open ocean. From what I have seen on the satellite photos for this year there are more melt ponds than usual. By my estimate if mean temps continue to drop below freezing we will see a minimum in the range of 5.0-5.2, it all depends on what happens in the next two weeks.

  26. I am so excited by all this concern about Arctic ice that I have forgotten what my guess was.

  27. LazyTeenager said on August 18, 2011 at 1:51 am:

    RACookPE1978 says:
    August 17, 2011 at 4:03 pm
    ———–
    BOTH reflect equally the radiation at the actual angles found in the Arctic where the ice is found.
    ————
    This claim seems to be based on the “sea is perfectly flat” theory. I prefer the “sea has waves” theory.

    By your theory we’d have to recalculate the insolation amounts for the tropics as well. Since the angles of incidence will be increasing, the tropics will then be shown to be receiving less than the currently accepted values. Since the area of the tropics is far greater than that of the Arctic, or even the Arctic and Antarctic areas combined, safe bet the net result is the planet is receiving less total insolation than previously thought.

    Congratulations! It may not be the total amount of Treberth’s “missing heat” but still you may have discovered where a significant chunk of it went. And since your theory results in the Earth receiving less net energy from the Sun, CAGW is now obviously less of a potential problem than previously thought as well. Thanks for the great news!

  28. The Weather Channel was talking about how parts of Fl could be under water by 2100.

    Large parts of Florida are underwater now, so that is a pretty safe prediction.

  29. Mr Bateman, I have believed for a long time that the loss of Arctic ice is caused by the oceans dumping heat. The last few solar cycles were energetic and gave the oceans a boost, this heat is migratory and is being dissipated by the melting of ice and the open water losing heat to space.

    This is a long lag system and the solar output at the moment is not optimal, this points to a period in the near future where a sudden drop in the temperature profile of the world may occur.

    The melting of the ice for me means a future cooling not a warming,

  30. steven mosher says:
    August 18, 2011 at 12:42 am
    Funny how everybody focuses on air temps.

    http://www.oc.nps.edu/~stanton/fluxbuoy/deploy/buoy21_deltaT.html

    its like people forget the heat capacity argument

    ———————————————————
    Hadn’t forgotten it Steven, just thought it was interesting that mean temp above 80oN had dropped below freezing earlier in the season than the ERA40 mean.

  31. Brian [August 17, 2011 at 11:25 am] says:

    “It’s not going to be long until it’s gone folks. The future looks dim. Even The Weather Channel was talking about how parts of Fl could be under water by 2100. I feel for future generations.”

    What no sarc tag? Oh that’s right, you really do believe this!

    It’s not going to be long until it’s gone folks. :: How long? And until ‘what’ exactly is gone? And for how long will ‘it’ be gone? One or two weeks in August or September?

    The future looks dim. :: What does dim look like, and what exactly looks dim? If you jack up the cost of energy and food I would say *that* looks dim, but somehow I doubt this is what you are talking about.

    Even The Weather Channel was talking about how parts of Fl could be under water by 2100. :: Parts of Florida that are at sea level are under water when it rains. Lots of beach is under water at high tide. Perhaps you know of something not normally underwater that will soon always be underwater. Please specify this location.

    And the Weather Channel? Puhlease! What a damn shame that it was destroyed by NBC and has been infiltrated now by the trolls at MSNBC …

    “On July 6, 2008, NBC Universal, Bain Capital and Blackstone Group agreed to purchase the Weather Channel from Landmark Communications.[2] NBC Universal also owned NBC Weather Plus, a rival service which was carried by and featured content from its local affiliates; that service announced its discontinuation three months later. Subchannels carrying Weather Plus have moved to the Local AccuWeather Channel, kept the Weather Plus engine, or switched affiliations (e.g., to This TV or the Retro Television Network). Some have shut down entirely.

    From November 2008 through February 2009, The Weather Channel terminated seven long-time on-camera meteorologists: Kristina Abernathy, Eboni Deon, Kristin Dodd, Rich Johnson, Cheryl Lemke, Mark Mancuso and Dave Schwartz. With the exception of Eboni Deon, all had been on the air for more than ten years. Three of them had been employed by the network for more than twenty years. In July, 2010, The Weather Channel terminated Bill Keneely, the last of the original on-camera meteorologists who aired on the network’s first broadcasts in 1982.

    Inevitably, the merger of NBC on-air meteorologists began in May 2009. Todd Santos, formerly of NBC Weather Plus, first appeared on the network on the second day of the month. Al Roker of NBC’s Today show began a one-hour morning program with meteorologist Stephanie Abrams as co-host, later in the summer. However for New York-based forecasting operations (those utilized for MSNBC and CNBC forecasts, for instance), the former NBC Weather Plus forecasting, radar, and graphics systems remain in place, with banners changed to fit the Weather Channel graphics scheme.”

    I feel for future generations. :: Which ones? The future generations that will be in a slightly warmer cycle like 1985-2000-ish or those in a cooler cycle like the 1960’s and 1970’s? I myself do feel sympathy for those living in the cooler cycles especially because of the high cost they will face in heating during brutal winters (kinda like now), especially if people like you add more taxes to their bills. Heating in winter is not optional, it is life and death. Cooling in summer (e.g. air conditioning) *is* optional and humans survived for millennia without it, even at the equator!

    Brian, it’s not too late to re-post your comment, this time using a sarc tag.

    ;-)

  32. Bloke down the pub?
    do you know what ERA40 data is?
    do you accept the physics models used to create ERA40 data?

    you have 50-100 watts of flux beneath the ice which will melt out 1-2cm a day of ice for a couple
    of months. Basically you have a race between bottom melt and top freeze. fresh water melt ponds on the top freeze at a higher temp so its an interesting race.

  33. One point everybody missed

    Data from the Advanced Microwave Scanning Radiometer – Earth Observing System (AMSR-E) sensor, processed by the University of Bremen, show ice tracking near 2007 levels. The AMSR-E instrument can detect small but widespread areas of open water within the ice pack in the Beaufort and East Siberian seas, because of its resolution (6.25 kilometers or 3.88 miles). Normally, NSIDC uses data from the Defense Meteorological Satellite Program (DMSP) F17 Special Sensor Microwave Imager/Sounder (SSMIS). F17 provides a longer time series of data, but at a 25-kilometer (15.5-mile) resolution.

    By switching to a higher resolution sensor you increase your extent decrease estimation.

    Like I said, its funny how people get distracted by air temps.

  34. steven mosher says:
    August 18, 2011 at 10:57 am


    you have 50-100 watts of flux beneath the ice which will melt out 1-2cm a day of ice for a couple of months. Basically you have a race between bottom melt and top freeze. fresh water melt ponds on the top freeze at a higher temp so its an interesting race.

    Concur. A very interesting race indeed! Between top cooling (from conduction to the air), top re-radiating (to the clouds and open-skies) and top evaporation (from open salt water, open fresh melt ponds), and top sublimation losses (from both ice and snow) … and heat gains and losses underneath (thermal conduction from the water, visible light transmission (should be very little if the ice is greater than 1 meter -> true?) … Any significant others that I’ve missed?

  35. From steven mosher on August 18, 2011 at 10:57 am

    do you know what ERA40 data is?
    do you accept the physics models used to create ERA40 data?

    Did you miss the new post about ERA40 being tragically flawed?
    Why would anyone accept those physics models as they currently stand?

  36. LazyTeenager says:
    August 18, 2011 at 2:01 am

    James Sexton says
    ———–
    First and foremost, arctic temps have very little to do with ice loss.
    ———–
    So this appears to be based on the “ice doesn’t melt when it gets warmer” theory.

    James are you going to impress us with a graph showing a decades long increasing trend trend in Arctic wind intensity?

    And a corresponding increase in the amount of ice floating around the Atlantic. And proof that the incease amount corresponds exactly to ice loss.

    Or is this just a gut feeling you have?
    ==================================================
    lol, sis, do you know how to read a graph? How much melting do you believe occurs in less than zero C temps? This year shows it quite well….. Further, look at the graph closer…. http://ocean.dmi.dk/arctic/meant80n.uk.php ….. notice that the summer temps are below the mean. (Being defined as 1958-2002) If arctic temps were the driving force related to ice extent, then ice extent should be somewhere below the mean of 1958-2002, all else being equal. If you’d lose your snarkiness for a second and consider the information I presented earlier, you’d have something a little more substantive to offer the conversation —— but that’s just a gut feeling. :-)

  37. RE: Data from the Advanced Microwave Scanning Radiometer

    Can it discern the difference between true open water and melt ponds?

  38. Extent is a measurement that essentially ignores melt ponds. Areas of open water or surface melt that comprise less than 85% of a grid or cell are considered ice covered. Thus extent is a VERY conservative measurement of true amount of ice.

    We’re looking at extent right now at 5.17 million km^2. Model forecasts over the next 10 days for Arctic temperatures and winds indicate higher than normal ice loss for this time of the melt season. Throw this in with some very thin ice across much of the ice pack ( the Polarstern measured ice less than a single meter thick on their just completed voyage to the NP) and you could see some large losses. 100k yesterday, likely another 100k today, and quite possibly below 5million by midweek.

    2011 is shaping up to be another 2007.

  39. Kevin O’Neill [August 23, 2011 at 6:21 am] says:

    “Thus extent is a VERY conservative measurement of true amount of ice.”

    Keep saying it and perhaps you and a few other alarmist bedwetters will believe this. Normal people realize that a windy day versus a non-windy day up there causes dramatically different outcomes in ice extent, thus blowing this metric out of the water as anything useful.

    I mean honestly, really really honestly, if one day there is 100 km loss and the next day is 50 km and then 100 km, do you not see the problem? It is ice cube roulette, nothing more. If the extent was to finish at 6 million you and your fellow AGW cultists would move on to cooking up some other scare tactic.

    “2011 is shaping up to be another 2007.”

    You say that like it’s a bad thing! Do you not realize that 5 minutes after the ‘minimum’ is reached the growing begins? All the Arctic scare stories boil down to how much open water exists for a week or so in September! Like I said before, unless Earth gets whacked bad by an enormous object onto its side like Uranus, the axial tilt means it will remain cold up there forever.

    “Uranus has an axial tilt of 97.77 degrees, so its axis of rotation is approximately parallel with the plane of the Solar System. This gives it seasonal changes completely unlike those of the other major planets. Other planets can be visualized to rotate like tilted spinning tops on the plane of the Solar System, while Uranus rotates more like a tilted rolling ball. Near the time of Uranian solstices, one pole faces the Sun continuously while the other pole faces away. Only a narrow strip around the equator experiences a rapid day-night cycle, but with the Sun very low over the horizon as in the Earth’s polar regions. At the other side of Uranus’s orbit the orientation of the poles towards the Sun is reversed. Each pole gets around 42 years of continuous sunlight, followed by 42 years of darkness.[49] Near the time of the equinoxes, the Sun faces the equator of Uranus giving a period of day-night cycles similar to those seen on most of the other planets. Uranus reached its most recent equinox on December 7, 2007.[50][51]

    One result of this axis orientation is that, on average during the year, the polar regions of Uranus receive a greater energy input from the Sun than its equatorial regions. Nevertheless, Uranus is hotter at its equator than at its poles. The underlying mechanism which causes this is unknown. The reason for Uranus’s unusual axial tilt is also not known with certainty, but the usual speculation is that during the formation of the Solar System, an Earth sized protoplanet collided with Uranus, causing the skewed orientation.[52] Uranus’s south pole was pointed almost directly at the Sun at the time of Voyager 2’s flyby in 1986. The labeling of this pole as “south” uses the definition currently endorsed by the International Astronomical Union, namely that the north pole of a planet or satellite shall be the pole which points above the invariable plane of the Solar System, regardless of the direction the planet is spinning.[53][54] A different convention is sometimes used, in which a body’s north and south poles are defined according to the right-hand rule in relation to the direction of rotation.[55] In terms of this latter coordinate system it was Uranus’s north pole which was in sunlight in 1986.”

    _Wiki_

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