>... you have to put a lot of energy (heat) against it to heat it up (or cool it down)

This refers to specific heat (energy required to change temperature) and is not the same as thermal conductivity.

>Ice wants to stay ice. this is why ice cubes work so well to keep drinks cool.

This refers to heat of fusion. Also not the same as thermal conductivity.

You could replace the ice in snow with different substances with lower specific heat, lower heat of fusion, and a melting point so high that melting is irrelevant, and it would still be a poor heat conductor due to the large air content.

It's wrong to say that water (or ice) is a poor conductor of heat because it takes a lot of energy to melt it. It's correct to say that water has a very high "heat of fusion" (latent heat involved in turning 0-degree ice into 0-degree water). Conductance refers to its ability to carry heat from a hot object on one side of it to a cold object on the other side. Snow (not ice) has very low conductance due to its large air content, the same reason house insulation works well; it has nothing to do with ice's high heat of fusion.

All thermal power plants (solar and fossil fuel) have significant inefficiency related to the difficulty of converting heat into work. So the turbine contributes to the inefficiency but isn't the biggest factor. Solar thermal power generation looks less good considering this.

For things where you really need heat, like cooking or heating water, you can avoid that inefficiency of converting light or heat to power; for example, lots of people heat their hot water by collecting heat directly from collectors on their roof. However, despite the increased efficiency, this isn't necessarily cost-effective compared to other means of reducing fossil fuel energy use--electricity is just a really practical way to move energy around.

Lots of data still has to be collected by hand. For example, I know people who measured the amount of water flowing in streams (on land in northern Alaska/Canada). In small streams, this is done by manually pouring maybe a cup of salt solution in the stream, then measuring electrical conductivity a few tens of meters downstream of there (conductivity is a proxy for salt concentration). It can take several minutes to complete the measurement, and if there's snow in the way, you have to shovel that out first.

Snow shoveling is a good mundane Arctic task; any time you want access to the ground, you have to shovel snow. Solar panels may need to be cleaned periodically too, and in many places they need to be mounted pretty high so they don't get covered in snow in the winter. However, anything that runs year-round north of the Arctic circle will need more than just solar panels + typical battery bank to run through the winter.

A shock is a significant discontinuity in pressure, density, and velocity. Viscosity means that nothing is truly discontinuous, so in sea-level air, "discontinuous" means a big jump in a distance of approximately microns.

Just a warning that the answer for "temperature effect on sound speed" will be totally different for air vs solids.

In air, sound speed depends strictly on temperature. This is because the bulk modulus of air is proportional to the pressure, so the sound speed is proportional to sqrt(pressure/density). By the ideal gas law, that means that sound speed is proportional to sqrt(temperature).

In solids, the effects of temperature on density and elastic moduli are not so simple as in gases. Also, in solids, there are both compressional and shear waves, vs just compressional waves in liquids/gases. Unfortunately, it's sometimes not clear from scientific writing on elastic waves in solids whether they're talking about compressional or shear waves (or both). In most cases I know of, higher temperature means lower elastic wave speeds because the effect on elastic modulus is stronger, especially for shear waves.

Aerosol emissions from wind instruments: effects of performer age, sex, sound pressure level, and bell covers

Abstract: Aerosol emissions from wind instruments are a suspected route of transmission for airborne infectious diseases, such as SARS-CoV-2. We evaluated aerosol number emissions (from 0.25 to 35.15 μm) from 81 volunteer performers of both sexes and varied age (12 to 63 years) whileplaying wind instruments (bassoon, clarinet, flute, French horn, oboe, piccolo, saxophone, trombone, trumpet, and tuba) or singing. Measured emissions spanned more than two orders of magnitude, ranging in rate from < 8 to 1,815 particles s−1, with brass instruments, on average, producing 191% (95% CI 81–367%) more aerosol than woodwinds. Being male was associated with a 70% increase in emissions (vs. female; 95% CI 9–166%). Each 1 dBA increase in sound pressure level was associated with a 28% increase (95% CI 10–40%) in emissions from brass instruments; sound pressure level was not associated with woodwind emissions. Age was not a significant predictor of emissions. The use of bell covers reduced aerosol emissions from three brass instruments tested (trombone, tuba, and trumpet), with average reductions ranging from 53 to 73%, but not for the two woodwind instruments tested (oboe and clarinet). Results from this work can facilitate infectious disease risk management for the performing arts.

Canals and reservoirs are artificial; their use increases water loss in dry places like California over what it would be naturally. As others have noted, reducing evaporation from them would not significantly affect precipitation elsewhere, but it it would make a big difference for the local fresh water supply.

Little bit of context for the question that i had to look up: alligators and crocodiles are in the same order but different families, and their most recent common ancestor was in the late cretaceous (65+ million years ago). So that's not exactly "distantly related", but certainly less close than I'd expect given how similar they are.

Most people are surprised to learn that most "hot" places in the US, like Atlanta, spend more energy heating than cooling (measured using heating and cooling degree days). https://www.climate-zone.com/climate/united-states/georgia/atlanta/

The answer to your question totally depends where you are and whether you're talking about agriculture or nature. In either case, plants care about moisture present in the soil vs moisture loss through transpiration. This is an American perspective, by the way.

Let's talk agriculture first. In some places, agriculture is rain-fed, for example the eastern US west of approximately the hundredth meridian (e.g., central Nebraska) and also the Pacific coast west of the Cascades and Sierra Nevada. In those places, rivers flowing by don't have much effect on soil moisture except at low elevations near the river--it's all about rain falling on the plants themselves. It is worth mentioning that in a lot of places, impermeable soil means that the ground can only soak up so much rain at a time. So if you get 3 inches of rain in, say, Virginia, you might store 1 inch in the soil and have 2 inches run off into streams, where it's not useful to farms (but may be useful--or harmful--to aquatic life downstream). This totally depends on the soil; sandy soils will soak up water whereas clay soils tend to be especially impermeable, and of course bedrock, rooftops, and paved surfaces don't absorb water. Counterintuitively, soil can be more impermeable when dry, so a heavy rain after a long drought may mean lots of runoff and not much water infiltration.

Natural plants are similar to rain-fed agriculture in that water in streams is not so useful to them, except in the riparian zone.

In other places (the dry western US), modern agriculture requires irrigation. Irrigation can come from rivers, renewable aquifers, or fossil aquifers (e.g., the Ogallala). For river irrigation, the Colorado river needs to be mentioned on its own because of the huge amount of land it irrigates and the huge amount of storage it has. In the Colorado river basin, most of the precipitation falls in mountains near the system's headwaters in Colorado and Wyoming, runs off and is stored in reservoirs, mainly in Lake Powell and Lake Mead (which have enough capacity to store a couple years of river flow), and is distributed to farms in dry places that would not support agriculture otherwise (e.g., California's Imperial Valley), plus lawns, golf courses, etc. Very little is allowed to reach the Gulf of California, a practice that devastated a formerly thriving ecosystem at the Colorado Delta. When we talk about drought on the Colorado river, we mean that less precipitation is falling than usual, meaning that reservoirs are low and still falling. Recovery from drought would mean more precipitation falling near the headwaters; agriculture in the Colorado basin is all about irrigation; given adequate irrigation, the dry climate for the farms can actually be a benefit (more sun, so more productive). Given the hole we are now in and the poor prospects for precipitation to increase in the future, we are probably going to have to adjust our expectations for how much water can actually be drawn from the river.

Other western river systems have parallels to the Colorado but are less extreme. In Idaho's Snake River Plain, for example, agriculture is mainly irrigated by the Snake River, tributaries to the Snake like the Boise and Payette, and renewable groundwater. All of these are mainly fed by snowmelt from the mountains. The region does get some snow and rain through the spring, and that does add moisture to the soil and help delay and reduce irrigation needs; however, it's just a fact of life in the area that the soil dries every single summer and you can't grow crops in the dry season without irrigation water. Reservoir storage (including year-to-year carryover) is significant, but smaller than on the Colorado (less than one year's worth of flow can be stored); the ability to benefit from water stored into the summer as seasonal snow is essential. In this area, recovery from drought mainly means lots of snow.

For fossil aquifers, like the Ogallala on the Great Plains, the aquifer will not be replenished on human timescales, so we should think of it just like we think of a mine: sustainable use is impossible, and once used up it's gone. In dry years, more irrigation water is needed, but the concept of drought does not apply to the aquifer itself.

Yes, business expenses broadly can be deducted as non-income. Mortgage interest is not a business expense; it gets special treatment that rent doesn't get. That's the whole point here.

All subsidies benefit both the buyer and the seller; the mortgage interest tax deduction is not unique there. I think the financial industry would survive just fine without this subsidy (and I'm very surprised to see corporate welfare being touted as a benefit to promote the mortgage interest tax deduction!).

The subprime mortgage crisis didn't happen because the banks weren't profitable enough; the financial system was destabilized by banks turning out to be insolvent due to years of accumulating toxic assets, meaning a sudden loss of confidence in the system.

Thanks. Could you please add clarifying text to your original comment, saying that this is for business use only? The vast majority of renters are not able to deduct any of their rent, and no renters can deduct all of their home's rent.

Tax breaks are often used as subsidies. This is not unique to mortgage interest.

>A business is not taxed on its expenses, only on profit. Does this make a business the beneficiary of a hidden welfare state?

As an individual taxpayer, I can deduct mortgage interest, but I cannot deduct food, clothing, utilities, or most other expenses (or rent, for that matter). Why single out mortgage interest among all the expenses we have?

Please correct me if I'm missing something, but 8829/schedule C is for business use only, if you use part of your home exclusively for work. Deducting your kitchen or bedroom's expense would be tax fraud. I've never heard of anyone legally deducting their rent on US federal taxes except for a home office used for nothing but work.

From the source:

>Use Form 8829 to figure the allowable expenses for business use of your home on Schedule C

I don't see why you'd say that. Renting is just paying the landlord for their service of giving you housing...just like you pay the grocery store for the service of giving you food, or pay the clothing store for the service of giving you clothes. Not everyone needs to own a farm; it's ok to pay someone else for food, and it avoids having to tie up a huge amount of wealth in a farm. Not everyone needs to own a home; it's ok to pay someone else for housing, and it avoids having to tie up a huge amount of wealth in a home. It's a personal decision, where for a lot of people (especially people who move a lot, or don't like being responsible for home maintenance, or just want a small place that doesn't cost much) buying a house makes no sense at all.

If your argument involves the phrase "building equity", having your equity tied up in a house means you can't put it in the stock market (where it would probably do as well or better than a house) or even a business. There are lots of ways to invest money and a home is not necessarily the best.

I am a homeowner (just bought this year and am going through all the first-year projects), so I get to deduct mortgage interest. Only homeowners get that benefit. Here's a list of essential expenses, shared by renters and owners, that I don't get to deduct from my income taxes: food, clothing, heating, transportation (in fact, I pay sales tax on most of those things). Yes, homeowners pay property taxes, but 1) those are often deductible on federal taxes, and 2) landlords' property taxes are baked into rent prices, so renters indirectly pay them too. And the really big one is that renters don't get to deduct their housing costs when doing income taxes!

So yes, as a homeowner, I do feel like the government is singling out people like me and subsidizing my housing expenses. I also feel like the government is putting its thumb on the scale and encouraging me to be an owner rather than a renter. Owning does have some benefits, but also some very big drawbacks--a big one being that as a homeowner, moving is a lot more expensive than a renter, so I'm less able to move in order to pursue better opportunities elsewhere. Another is that maintaining a home is a lot of work and money; I'm relatively handy and work hard at it now and am getting better, but I know my old landlord could do things more efficiently and cheaper than I can (so if I still rented, less time and money would be spent on home maintenance). Finally, because homeowners generally have more money than renters, these benefits are mostly going to reasonably well-off people.

Correct link: http://www.seas.ucla.edu/stenstro/Bubble

The source says that this only applies to bubbles >0.1 cm radius.

The source appears to be class notes, and does not cite sources itself. The idea that ascent rate is independent of bubble radius is counterintuitive to me given how Rayleigh drag works (normally appropriate at high Reynolds number). A quick search I did failed to find anything to confirm this. So, I'm leery of accepting this claim uncritically, and I'd like to see a better source here and explanation of the physics.

Another well-read American here. This is the first I ever heard of Anglo-Saxon being a racist buzzword (as described here). Not denying that it exists, just that the racist buzzword use is not how I'm used to hearing it used. The racist use seems illogical to me because the term excludes Germanic or Nordic heritage, which modern racists usually are fine with.

I've heard Anglo-Saxon used in a few senses in American writing, none of which make any sense or actually pertain to Anglo-Saxon ethnicity (i.e., not Norman, Norse, or Celtic):

• In global politics, "Anglo-Saxon world" basically meaning the close ties between US, UK, Australia, NZ, and Canada
• Especially in the northeastern US, describing white families with British colonial roots, as opposed to heritage in post-independence immigrants (as in White Anglo-Saxon Protestant, "WASP"), usually with the implication of upper class, "respectability", education, and a certain uptightness or reserve
• In the southwestern US, "Anglo" meaning English-speaking Americans with roots elsewhere in the US, as opposed to the hispanic and indigenous people who were already there before the Mexican-American war (not common anymore in my experience).