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PaperclipPerfector
7d ago
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I dislike DST, but it'd be nice if sunsets were an hour later in Winter...
Annual cost of daylight saving time (DST): peer-reviewed and policy-analytic estimates for the U.S. range roughly from a few hundred million dollars to several billion dollars per year depending on which effects are counted.
$672M/year).Cost to extend daylight by 1 hour using space‑borne mirrors (back‑of‑envelope):
1e3 W/m^2 × 1e7 m^2 × 3600 s ≈ 3.6×10^13 J (10^10 Wh ≈ 10 GWh) of additional daylight energy delivered to that footprint. *Mirror size and launch/placement costs (order-of-magnitude):Wouldn't actually extending the day with a giant space mirror significantly mess up the climate, plants, and animal behavior?
Most of the cost in DST is in switching twice a year. I personally prefer summer time, but would be happy if we just picked one.
Most of the rest of the cost is schools and work places picking opening hours inappropriate for the location, or poor indoor lighting. Fixing your indoor lighting and buying a sunrise alarm or just a 'smart' bulb if you are cheap, seems way easier than spending your days advocating for space mirrors.
My interior lighting is bright enough and Standard Time has an earlier sunrise than DST - the tradeoff of DST is a later sunrise for a later sunset.
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I was a more strident advocate for DST being dumb, but I now think it is more appropriate, as trying to get kids up in the morning when it is pitch black outside is pretty rough.
In a world where school started at a more reasonable hour you probably wouldn't need it, but then there's all the knock-on effects from school also functioning as daycare...
DST makes this problem worse, not better?
Maybe he's referring to the many proposals for permanent DST (which would have winter sunrises around 9AM in a lot of America).
That would be very bad -- 'solar noon occurs at 12:00 somewhere in the vicinity of the middle of each time zone' (with maybe the odd carve out for quirky borders or whatever) is the only thing that makes any sense at all.
A 9 AM sunrise is only true if you define most of America as Seattle, which would have a 8:55 AM Sunrise on the solstice. For an arbitrary selection of Northernish American cities I get:
On the solstice, DST referring to the permanent summer time scenario, ST referring to winter time.
Insisting on solar noon being 12:00:00 is a bit of an anachronism. If you were a farmer back in the day you would tell time by a rooster and the sun, and were used to getting up before the sun in the winter. You also had limited artificial light and heating, and did not have to commute by car for work and kids school. The modern school and work schedule is set by some combination of tradition time immemorial, school effectively being day care, traffic congestion spreading, and position in time zone.
A teenager with after school activities will be waking up before the sun and coming home in the dark regardless. In the permanent summer time permutation you might have the chance of getting some sun after volleyball practice or whatever. From the parents perspective you're probably the first person your teenager sees in the morning, and they take their rage from being cranky waking up before the sun out on you. They are probably slightly less cranky latter in the winter when the sun rises slightly earlier in the standard time scenario. A productive adult, with adult responsibilities, and a normal scheduled is almost certainly waking up before the sun in all these cases. If you live at least as far south as San Francisco you might have some chance of at least catching twilight (the diffuse sky radiation kind though no hate if the vampire fantasy is your thing) on your way home in a permanent DST scenario.
Somehow people in the Alaska Time Zone and China Standard Time make do with extreme variation in solar noon. I suspect because once solar noon is sufficiently decoupled from clock time, work places and schools are finally forced to set hours appropriate for the location rather than relying on conventional hours from before modern lighting.
Both permanent DST and ST suck in the winter, but not particularly because of the timing of solar noon. Switching also sucks, and is where a decent amount of the traffic and health impacts come from.
The fundamental "problem" is that day length in winter is roughly the length of the work/school day, so you don't have any extra daylight to "save" for waking, free time, and commuting. Thus OP suggesting creating more daylight with giant mirrors. I personally hope most of the problem is solved by the increasing adoption of high quality LED lighting and dirt cheap microcontrollers, allowing granular spatial and temporal control over peoples lighting environments.
Not sure you realize how late sunrises are in the western edge of the Eastern time zone. It would be ~9AM in nearly all of Michigan, nearly all of Indiana, large parts of Ohio/Kentucky and western PA (Pittsburgh would get to 8:40 at worst). Even Atlanta would be after 8:30 for a few weeks in December.
Rereading your previous post I see you did say "a lot of America" and not "most," I apologize if I misrepresented what you said.
The list of cities I chose was arbitrary, but the Detroit metro is arguably of comparable scale and one of the places that would have the latest sun rises if the current time zone boundaries were to remain static.
Of the places you mentioned Michigan and Indiana are (basically) fully west of the 82.5°W meridian, which would be the natural boundary for the UTC-5/6 division based on solar noon. For Ohio major population centers Columbus and Cincinnati, and for Kentucky population centers Louisville, Lexington, & Bowling Green are also west of 82.5°W. Atlanta as well, though places south of 35°N have less of a problem with insufficient daylight.
This means they are already effectively living in daylight savings time in the winter relative to solar noon, which would be UTC-5. In the summer when they go to UTC-4 they are living in double daylight savings or something. Somewhat ironically, permanent UTC-5 seems to be what some people in Indiana prefer, they just call it Eastern time with out daylight savings time observance rather than Central time with permanent daylight savings time. Neither of which is what people in actual Eastern time or actual Central time currently observe. If the US really were to adopt year round daylight savings Indiana should almost certainly move to be part of the central time zone, which is where they were historically and by meridian. This would solve the problem for people who live in the Chicago-Gary metro having to be split of from the rest of the state. The current situation in Indiana with 11 time zones, and hundreds of previous permutations, is ridiculous and as far as I can tell only justified by trying to assert their independence from Chicago-land.
Indiana is the most egregious and should not be in Eastern time even under the current system. Tennessee, Kentucky, Ohio, and Michigan should probably move to Central time under permanent DST. Ohio and Michigan would then have the same sunrise they have now in the winter. Tennessee and Kentucky would gain the advantage of not being split in timezone.
Pittsburgh would have a late sunrise, but not worse than those poor people who live in the upper peninsula of Michigan now. Atlanta, sure but nearly 10 hours of sunlight on the shortest day of the year isn't really that bad to begin with.
While I do prefer permanent DST to permanent standard time, I am somewhat sympathetic to people who prefer standard time. Essentially there are people who have relatively early schedules who currently commute both ways in the dark during winter. There are people who have relatively late schedules who currently have some daylight on their commute in. Under permanent DST the early people gain the sunlight on the way home, at the cost of the late people who are now the ones commuting in the dark both ways. What I have a problem with is people who post exclusively about the cost of a late sunrise without acknowledging that shifting the clock affects more than the sunrise on the winter solstice. Or that no amount of changing the clocks will actually produce more daylight or make everyone happy. Just ask the people of Indiana. Maybe we should just produce more daylight with space mirrors.
When you then population weight the effects DST vs. standard time there are clearly tradeoffs, but the net effect varies by study. The only consistent thing they find is that changing the clock twice a year produces a measurable and negative effect. Permanent DST vs permanent standard time is a tradeoff between relatively early schedule people and relatively late schedule people. Changing the clocks twice a year gives everyone (very minor) jet-lag. It's mostly an inconvenience, but at the margins results in excess deaths and economic losses.
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If you're sending up space mirrors to orbit in order to light your cities, you can just as easily send up space sunshades to the Lagrange point in order to fine-tune global temperature - blocking only 2% of sun light from reaching the earth would cancel global warming. You'd also need less sunshades than space mirrors, since the sunshade always deflects sun light, while the space mirror supposedly only puts light onto the planet for a few hours per day in winter.
But yes, it would mess with plants and animals - though probably less than current light pollution does.
I'm pretty sure that indiscriminate general shading of the planet would substantially disrupt crop production as well as wild flora. For global warming geoengineering purposes you want to increase albedo in the IR range, but retain the spectrum primarily involved in photosynthesis.
If you are only using the mirrors to light your cities, it also seems highly pointless. The biggest direct cost with going to work or school with limited daylight is traffic crashes. If you are only interested in lighting limited areas, we already have the ability to do that it's called a lamp. Using fully shaded and cutoff lensed high-mast lighting limits light pollution and you can install them over the highways leading into the city. If you've ever commuted into a city by car it should be clear the areas where crashes occur due to insufficient lighting are on the unlit highways running in, not the relatively well lit city core.
Using a giant mirror to illuminate an area would also probably not produce the pleasant light people associate with a mild partly sunny day. It would practically be more probably like the light from a full moon, which will not fix the sleep problems and productivity losses associated with short winter days. For people with seasonal affective disorder you need something way stronger either something like a Lumenator or moving closer to the equator. Blasting a whole city with noon-levels of irradiance so a bit of light can trickle in through some peoples windows seems way less efficient than just having people who need it replace their old lights bulbs with corn bulbs.
Agreed on all points, maybe my original answer should have included the remark that both mirrors and sunshades are pretty dumb - but fun to think about.
To be pedantic, the sunshade-at-Lagrange-Point-1 idea would really just dim the sun by 2%. No matter if you use thousands of independent sunshades or one big one, when viewed from Earth it will only occlude a tiny part of the suns disk. Every spot on earth would receive 98% of normal sunlight. This wouldn't "substantially" disrupt crop production, it would just diminish it by around 2% (naively - except in cases where the limiting factor is available water or soil nitrogen/phosphorus or pests/weeds or ...). Making a sunshade that's larger but transmits the red and blue wavelegths relevant for photosynthesis would be smart, but probably even more ludicrously expensive than just having a thin film of aluminum on a polymere membrane which indiscriminately reflects all sun light.
Ultimately, if it matters you could also pretty easily "turn off" a sunshade by flipping it 90° (you probably need this capability anyway, because you have some degree of maneuverability in space using radiation pressure). If you really need a boost to the global growing season a little, you could always just turn it off.
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