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97

Make the Legend last through the ages So, Merlin telemagicks to 5000 years ago, presents the sword-in-cement LEGEND to some fancy king. Then he rigs up some scenario where the sword is found. People try and fail to remove the sword, the legend spreads. Merlin then causes some event (flood, landslide, magic POOFing, etc) to disappear the sword. The sword ...


93

Merlin knows about metallurgy, and will place in the immediate surroundings of the rock (or even IN the rock) a sacrificial anode made of magnesium, aluminium, zinc or another suitable metal. A galvanic anode is the main component of a galvanic cathodic protection (CP) system used to protect buried or submerged metal structures from corrosion. By simply ...


70

Can there be hereditary Servants of the Sword? These folks would live nearby, working the earth etc but they take responsibility for periodically going out to visit the Sword and putting a fresh coat of grease on it. Maybe they could have special hats - worn only for the sword greasing, you know.


70

What your son wants, and in fact you describe /and when their opponent is vulnerable for the final blow, will say: "See you next time" and go home./ is counting coup Any blow struck against the enemy counted as a coup, but the most prestigious acts included touching an enemy warrior with the hand, bow, or coup stick and escaping unharmed.1 Touching ...


59

Getting caught in a thunderstorm is the most likely cause. This can happen even to experts if they are incautious enough to take risks with the weather. Here's an example with a paraglider. (I'll see what I can find for a hang-glider) Ewa Wisnierska was sucked into a powerful thunderstorm while training for the world paragliding championships in ...


57

Let's say your magical sphere has radius $r$ of 10km (so just poking up into the outer atmosphere) and is at a temperature $T$ of 1,250K (so glowing a nice warm yellow). The total radiative heat flux from the sphere is given by: $$ Q = \sigma T^{4}. 4\pi r^2 \approx 1.7 \times 10^{14} \mathrm{W} $$ Where $\sigma$ is the Steffan-Boltzman constant. A ...


55

Something like this has actually happened once already 100 years wouldn't be enough to turn the Sahara into a savanah, but it would be a good start. From this source we read the following (emphasis mine): But around 10,500 years ago, a sudden burst of monsoon rains over the vast [Sahara] desert transformed the region into habitable land. This ...


52

The eye is a region of mostly calm weather at the center of strong tropical cyclones. The eye of a storm is a roughly circular area. It is surrounded by the eyewall, a ring of towering thunderstorms where the most severe weather and highest winds occur. In strong tropical cyclones, the eye is characterized by light winds and clear skies, surrounded on ...


51

Let's assume for a moment that there are bacteria living in clouds. These have to feed on something, but nutrition in clouds is scarce. The chances of collecting molecules with nutritional value increase with the surface area that can be used to collect them. Sometime during the endless evolution some bacteria managed to excrete a slimy substance that can ...


51

A wobbling pulsar will do the trick. Pulsars emit a lot of energy in narrow beams that come from their poles. The slowest ones flash every few seconds; make its tilt wobble so that it is not pointing at the planet all the time. In addition, wobbling causes the pulsar to shoot at different points of the planet's orbit through time. The planet is hit when the ...


45

Plant respiration Rainforests are famous for making their own rain. Plants transpire something like 98% of the water they take up. When you have a lot of plants, and it is already pretty humid, the result is lots of mist. Cold ocean currents Fog can form when the difference between the air temperature and dew point is less than 2.5 C. Water vapor in the ...


41

Let it rust. Seriously. A thick chunk of steel is already going to last ages without any special treatment. It will corrode on the outside for sure, but this adds to the authenticity of just how old it is. Maybe build a gazebo over it to keep the absolute worst of the weather off. It'll be way more exciting when "he whom the wizard deems worthy" finally ...


40

Different approach, after the Comment on my other answer: Maybe that's just how immortal (or very, very long-lived people) always fight - it's how it's always been. Dwarves have fought each other like that because, well - for a human with a finite time to live, dying for a cause to make the (short) life of their children better may seem like an OK deal. If ...


39

Your desert glass pebbles are volcanic glass. In the US they are called Apache Tears. source These are unpolished, as found in the desert. When polished they are a very beautiful deep black and suitable for use in jewelry. Some of the round ones in this image ones look pretty close to that without polishing. https://en.wikipedia.org/wiki/Apache_tears ...


38

Supernova. A type II-P supernova maintains a fairly constant brightness for several months, and one at an appropriate distance (something like 500 light years) will be as bright as the full Moon for that time period. It will need to be on the opposite side of your planet from its own star, as seen from where the planet is in its orbit. Betelgeuse will do the ...


37

You're in luck! We already have this action on Earth, in the Atacama Desert. Fog rolls in from the ocean, but the mist is so fine it doesn't fall as rain, hence preserving its desert-hood. Only a few plants are able to take advantage of the mist, so it still comes across as "deserty". There is a little lizard which lives there which has weird horns ...


37

Decrease Gravity Explanation: The water droplets we experience on earth are mostly so small because of gravity: when a water droplet becomes too big, gravity rips it apart before it can get bigger (like when you're not quite closing a tap, the only reason it doesn't get bigger is because the mass of the droplet is bigger than the force "gluing" the water to ...


37

What keeps my planet's water from irreversibly concentrating over time on the frigid wastes while the rest of the planet dries up? When ice piles up, it will exercise pressure. The closer to the terminator, the less the ice. As a consequence, pressure gradient will tend to push the ice sheet toward the terminator, where it will melt, returning water to the ...


36

Not sure if this is what you're looking for, but what about geysers? There'd obviously have to be a ton of them (and maybe some one with more of a science background can speak to what that level of seismic activity would do to the earth), but that'd be a potential way to supplement evaporation. the way I envision it, the world is like ours except for it ...


36

Mount Kilimanjaro is located close the equator (03°04′33″S 37°21′12″E) but its 5895 m high top is covered with permanent snow . Even better, the Mauna Loa, located on Hawaii Island, can give you a good estimate of the distance between the snow and the beaches. Mauna Loa is the largest subaerial and second largest overall volcano in the world (behind Tamu ...


36

Winter warfare (at given temperatures, which I would not call "Arctic") maybe uncommon, but absolutely realistic. For example, in the XIII century, Batu Khan's conquest of Rus' (a predecessor of Russia) was conducted primarily by winter campaigns, when temperatures were certainly plunging below -10F/-23C. Steel is not particularly more brittle at these ...


35

That is a lot of rain Runoff will carve rivers as excess water goes to the ocean. Take a look at the basins to see what will happen. It appears there will be five basic river systems. There will be an Algerian system, gatheringr rainfall from the north and west of the Haggar ranges and emptying into the sea in southern Tunisia. There will be a Libyan ...


34

There are 3 types of natural glass: obsidian (volcanic glass), impactite (meteor glass), and fulgurite (lightning glass). Naturally round impactite is virtually unheard of. Impactite tends to have strong striations in the direction of impact that gives it more of a cleaved shape. It is also very rare for it to be transparent. Technically, a round ...


33

Eucalyptus trees can form bubbles when it rains Combine a eucalyptus grove with rain and a high wind that blows the bubbles away as soon as they form and you have a rain of bubbles somewhere down the line. Video - Why do trees blow bubbles?


33

Salt. Also, ice. But not the normal kind. Cloud seeding is a pretty cool technique, and involves blasting ions into clouds to make them rain. Normal salt (sodium chloride) is effective, but there are a few others which make for more effective draconic breath weapons, like calcium chloride (eye irritant), silver iodide (also an eye irritant) or solid carbon ...


31

Deserts next to mountains are in part due to the rain shadow. As moist air rises across a mountain range, it rains, and that happens on the windward side of the mountain. The leeward side becomes a desert. So make sure that the prevailing winds are parallel to the mountain range, not across it, and perhaps that the land rises in the direction of the wind. ...


30

The conditions of hurricanes are very harsh and easily become a trouble for any surface going ship. They are even that dangerous to ships, that only the most specialized ships go through them at will - and these ships are made to withstand harsh environments by design. Most of the ships that can cope these weather are modern service vessels for offshore wind ...


27

At least 400 ft deep. A similar question was asked on reddit. To quote U235EU, who paraphrased the US Navy Submarine FAQ (now unavailable): Violent storms may be felt as deep as 400 feet (see item 21). The deepest we ever felt surface effects was about 150 feet and it was pretty good sized storm on the surface above us. That being said, multiple navymen ...


27

Ring around the star. from https://commons.wikimedia.org/wiki/File:Fomalhaut_B_entire-Hubble_Telescope.jpg Just as a planet can have a ring around it, so can a star. If you were in the same orbital plane as the ring and it was between you and the star, it would shade you. Consider the situation of the outer shepherd planet in this schematic of the ring ...


27

The remains of an ancient Dyson swarm Not quite natural, but mostly non-technological. If a prior civilization had constructed a Dyson swarm around the system's star, the light coming from the star might be heavily occluded. Assume the sun is >10X hotter than ours (or the planet is much closer in), and there are enough collector bodies in the swarm to ...


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