Hot answers tagged

33

What does it take to reduce the salinity? The salinity of sea water is around 35 g/kg. There are around 1,350,000,000 km³ of water, so roughly 1.3x1021 kg of seawater (1 kg/l, which is a bit off for saltwater of course, probably by 35 g). Which contains about 4.7x1019 kg of salt. To reduce the salinity to just 34 g/kg, you need to extract 1.4x1018 kg of salt ...


19

The residue dry powder you refer to is salt. Salt is toxic to most plants. The United Nations claims the world is already losing 2000 hectares per day of farm land to salt-induced degradation. This is land that is used to feed people. In some situations, salt from affected lands can contaminate underground sources of drinking water, which will affect people, ...


9

The oceans are salty because the slightly acidic rainwater dissolves minerals from ores and rocks and runs into the sea. This is a continual process, a consequence of erosion. However, the salinity of the oceans has been stable for millions of years, indicating that there is an equilibrium between processes in both directions. Salt is removed from the oceans ...


7

Short answer: air, land and water take a while to cool down (or rise in temperature; we see the same thing happening with July and August being the warmest months on average – not June, while June 21st is the longest day). In December, the fall just ended, and everything is relatively warm. Also, depending on how far North you go, the difference between day ...


5

Why are January and February the coldest months although 21 December is the shortest day? For the same reasons that the warmest part of the day generally occurs hours after noon. The daytime temperature only can start decreasing after the outgoing thermal radiation exceeds the incoming solar radiation. Another reason is that water, ground, and even the ...


4

Waterlogging is a situation were soil is either fully or near saturated most of the time, the air phase is restricted and aerobic conditions prevail. Waterlogged soil may appear dry on the surface. The soil does not need to be submerged to be waterlogged. Flooding is a temporary submersion of land by water. The duration of a flood may be very short, such as ...


3

Rough calculations: A 747 burns about 10000 kg of fuel an hour. Assuming it burned hydrogen at the same rate it would produce about 100000 kg (or litres) of water an hour. Flying at 1000 km/hr that means it produces 100 litres of water per kilometre of flight, or 0.1 litre of water per metre. Lets assume all of this water drops vertically below the plane in ...


3

No, not really. In simple terms, to be soluble in water, Pb must be in contact with it. But most of Pb is stored within the Zircon lattice, where water cannot diffuse through. For example, many zircons in metamorphic and magmatic-hydrothermal settings experience supercritical fluids, but preserve their U/Pb ratios (e.g. inherited cores in metasedimentary ...


3

I hope this thread is not noticed by our good friends in Australia, who might point out that in their frame of reference January and February are not noted for their coldness! You might be interested to know that there is an astronomical effect which the other answers have overlooked: on about January 6th, the Earth passes through the perihelion point in its ...


3

There are two reasons for this surprising finding: Compaction. Once you have high pressures at depth, the less dense material goes up. Take a bucket of water, put sand in it, and squeeze the sand really hard. Water goes up. Then, you'd expect no water at depth of several kilometres. Even if you somehow had free water at these depths, the expectation is that ...


2

I have gone over these in a fishing boat many times. I often use this as a fish locator with some shoaling fish around the Uk. One side to the other does show a difference in water temps on the temp sensors fitted to the hull. It is my belief that these lanes are caused by differing temperature of water columns and an upwelling on the surface, between the 2 ...


2

Where am I wrong in my assumption about natural water distillation (i.e. is rain water not as clean as it should be in theory)? Generally, rain water is pretty clean. That is not an issue. Plus, we treat ground water and reservoir/lake/river water, so we could easily treat rain water. What you really fail to miss is that ground water and reservoir/lake/...


2

It seems that attenuation is much greater at ultrasound frequencies: 50 khz 12-15 dB/km 0.5khz 0.024 dB/km It depends on what distance and resolution you need.


2

Nothing really prevents water from existing deep inside Earth. We have direct evidence that it does, even in the mantle. Evidence for such water may be found in Ice VII inclusions in diamonds[1]. Because of their great mechanical strength, diamonds formed in the mantle retain GPa-level pressure within their lattice, so when they come to the surface and ...


2

Before the 1960s, the size of the Aral Sea was relatively consistent. However, the Aral Sea went through some "dry spells" during the 1st and 3rd centuries BCE. Going even further back, the Aral Sea dried up during the Early Pleistocene and was "refilled" during the Early Holocene. In other words, the Aral Sea probably looked the same in ...


2

Air is affected by friction. A brief search of AMS journals shows over 14,000 times friction is mentioned. How it is manifested in the equations that describe the atmosphere is complicated. Let's think of wind as 'air moving' or perhaps space moving which air occupies. At some point, called the roughness length, the wind is 0 m/s (or knots or mph). If such a ...


2

Desalination of ocean water costs energy; beside fresh water, you gain salt. With some additional energy invested, you could purify this salt consisting to large extent of sodium chloride (NaCl) which may be used as table salt. In other places, you mine for rock salt from underground mines, and equally perform a purification of salt, yet without the ...


1

Think of what happens with the fresh water that we extract via desalination. It's used for drinking, general water supply, farming and some other industries. In either case it will either eventually evaporate and eventually end up in the ocean or it is discharged back into the ocean. Some water is of course lost in the process, but it's a relatively small ...


1

Jet fuel is hydrocarbons, so their exhaust is partly water, which is responsible for the visible contrails. How Airplane Contrails Are Helping Make the Planet Warmer suggests that the main climate effect is warming, not rain.


1

Optical LIDAR systems for marine use are being developed and are being used for accurate mapping of archaeological remains under water. See https://optics.org/news/8/3/26. However if a sonar is too big and impractical, I imagine oceanographic LIDAR is similarly out of scope.


1

VLF-EM is a perfectly valid technique for helping an expert decide where best to locate wells in geological environments where water is largely flowing in fractures. Typically it is a useful technique in fractured bedrock where a successful water well needs to intercept connected fractures or fissures. In other geologies, for instance porous sandstones, it ...


1

In the USA there are two classifications of airborne pollutants. They are Criteria Air Pollutants There are 6 separate air pollutants. These make the bulk of the regulation, especially for the Clean Air Act. Each pollutant has different standards to adhere to. Examples include lead, ozone, and particulate matter. Hazardous Air pollutants This is a list ...


1

It is called an aquarium, put what ever you want in it. With natural waters you have a good chance of collecting dragonfly larva , which will eat about anything else you catch including small fish. Chances of mosquito larva are low in my experience. I don't know why you would not want frog or toad tadpoles ; I have a couple very small feral ponds in my yard ...


1

Taking water out of the sea does require energy to lift it even if it's destination will eventually be below sea level. The dam idea of retaining rain water would require energy and resources for the production of the dam and require the loss of usable land. That is not the best dam way to approach this solution. Removing water up stream, from say the ...


1

The definition of a solute that is capable of dissolving in a solvent is that the force of attraction between the atoms in a solute are not strong enough to keep the molecule together when surrounded by the many negative and positive partial charges that make up the solvent. I don’t know exactly how many ion-dipole bonds Cl- and Na+ form with H(partial ...


1

Agricultural water is largely Fossil Water, which took tens of thousands of years to accumulate and industrial activities have used it in a century. Saudi Arabia is abandoning programs to grow wheat that achieved self-sufficiency but depleted the desert kingdom's scarce water supplies. Going from the 6th largest exporter to NO more. Humanity derives water ...


1

We have TONS OF water. question is .. Is it potable does withdraw rate of water capable of being sustained by periodic recharge (Rain/percolation) Because storage capacity How much water do you need/society Industry/agriculture are the largest water users...... human personal needs (drinking/bathing) surprisingly low. Africa, has been predicted to have 75 ...


1

Answer #43 above is absolutely correct. Unless water molecules are split (disintegrate) into hydrogen and oxygen, they almost never leave Earth into space. We have practically the same amount of water on Earth as it had when first created. After evaporation, it returns as rain. Every time. Every place. This is why I become crazy when government officials ...


1

The air temperature is 5 degrees. The water temperature is not. Same reason a bowl of soup or cup of coffee stays hotter than room temperature for some time before it cools down to room temperature. Take that bowl or cup and expand it to the size of a lake.


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