# All Questions

4,743 questions
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### What is the physical meaning of second moment of wind velocity?

I have been reading some documents about meteorological data and many of them mention the second moment of wind velocity. I guess it has to do with the way the wind is changing but in such case I ...
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### What is the significance of amphidromic points related to tides?

On reading about tide formation and the role of moon's gravitational force, I came across the term amphidromic point. Could someone please elaborate this concept?
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### What are these underwater structures near 6°N 85°55'W

While google earth-researching the sea floor near Malpelo and Cocos Islands (Colombian and Costa Rican Pacific Ocean), I came along these strangely geometrical structures in the sea floor, located ...
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### What are some organic-approved solvents I can use to make my own liquid agri-mixes? [migrated]

I have a few ideas for organic pesticides/fungicides etc. They're intended to be sprayable, and ideally soluble in water. What are some organic-approved solvents?
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### can somene identify this rock? [on hold]

DOn't know where it came from, tried google image search, nothing. Gray, smooth with brainlike texture
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### Is there standard methodology for assessing how environmentally friendly a particular lifestyle is? [migrated]

The headline says it all, I'm looking for a standard way of assessing a lifestyle against environmental criteria. I'm thinking of some sort of lifestyle questionnaire that will produce a score from 0 ...
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### Relationship between sediment concentration of flow and erosion - streampower equation

I am trying to understand how the sediment concentration of a flow affects erosion. I stumbled across this paper by Bagnold (1968) today that uses a form for the stream power equation that I had not ...
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### Why does chlorophyll only come in green? [on hold]

Plants do not only come in green but chlorophyll does. The pigment in the plant creates other colored plants other then green. Could a plant grow under an alternative light spectrum like a green sun ...
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### Rock identification Help Needed [on hold]

Found them down by the river and would like to know more about what they are or what they're callled? Thanks
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### What type of rock is this [on hold]

![I found the the rocks is Eastern Arizona by the Black Mesas. They are white with a few orange patches. The inside kind of looks like quarts.
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### Would hydroponic megaplexes be a possible answer to the CO2 portion of the environmental/global climate change issue? [on hold]

Hydroponic agriculture can make use of vertical space better than traditional agriculture, making volume more important than horizontal area. While we typically don't take this to the extreme, we ...
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### Ekman mass transport and relative depth

The mass transport associates at Ekman's problem is the integral of velocity times density from surface (z=0) to the bottom of the Ekman layer (z = -De). In many books i find that i have to take 2 ...
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### How is the difference in crust and mantle composition explained?

We know that the composition of the crust is SiAl and SiMa and the one of mantle is mostly ophiolites, but why? Which are the geological processes that make this difference exist?
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### How Good is The Evidence For Snowball Earth?

Some geologists say there were times between 770 million years BP and 630 million years BP when ice ages were so profound that the Arctic and Antarctic ice caps met at the equator. This is called the ...
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### what do you think this was? [on hold]

![ is this a fossil? theres only 2 visible material in it. the white one that was been coated by the greenish substance. some parts appear brown because of the thin layered coating of the green ...
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### What is the line crossing the Pacific Ocean that is shown on maps?

The picture below shows an imaginary line on the globe which crosses the Pacific Ocean and works as a rough separator of the Eastern and Western hemispheres. What is this line called in English? I'm ...
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### Rock identification Help [on hold]

Found them down by the river and would like to know more about what they are or what they're callled? Thanks
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### identification help please [on hold]

So I was collecting golf balls in a river and thought it was a golfCan someone help me identify what type of rock this is? what type of rock is this that I found
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### Is there a hemisphere where there's more land than ocean?

From a previous question, around 40% of the northern hemisphere is land. Would there be a plane splitting the earth into two equal parts, where in one part there are more land than ocean?
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### Molten salt seas on the future Earth

As the sun gets brighter, the oceans are expected to evaporate by the next billion years or so (the vapor slowly gets stripped off into space). The salt, which is less dense than most rocks, will be ...
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### Rock ID: Found on South Downs in East Sussex UK

I found this slightly rude-shaped rock/stone on the South Downs in East Sussex, UK years ago. It was embedded in a chalky path and came out in the two pieces in the photo. It is heavy for its size (...
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### What kind of rock is this being eaten by a rock-eating worm?

The New York Times article This Creature Eats Stone. Sand Comes Out the Other End. describes the shipworm Lithoredo abatanica, an organism that appears to "eat solid rock". It links to the item in ...
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### can anyone help pretty please?? Is this Gold..fools gold just another metal?? 😊 [closed]

can anyone help pretty please?? Is this Gold..fools gold just another metal?? 😊
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### What is the Carbon Footprint of not changing car oil?

I am on my second vehicle that I have stopped changing my oil after the car has been broke in or around 90k. The first car I made it 400k miles before the rear end went out. The second car I'm at 130k ...
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### How older is this snail shell possible could be?

Last weekend I was in Xınalıq(the village in Azerbaijan) and found this snail shell. I am wondering how old is this?
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### Historical isobaric charts?

I am looking for a small-scale isobaric chart, which encompasses central Africa. I am interested in the time span of the past few months. Do you know where to find it? Thanks
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### Quickly breeding oysters to combat oceanic pollution?

I've been doing some wikipedia binging and it's come to my realization that it may be in the Earth's best interest to raise the world oyster population as quickly as possible. The basis for this is ...
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### Climate consequences of very large asteroids striking the Deep Ocean

For every asteroid or meteorite that hits dry land, two hit the sea. If a Manicouagan-sized asteroid struck the deep ocean (but not above a trench),how would the H2O vapour, chlorine, iodine bromine ...
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### Presence of Diabatic heating term in the continuity equation

The tropical circulation paper by Gill (1980) approximates vertical velocity as the sum of pressure and diabatic heating terms (equation 2.5 at page 449). Since the pressure is already a function of ...
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### Application of vorticity tendency equation

I have a question about the dynamics of westward propagating vortices. In meteorology, the vorticity tendency is often used to explain the westward propagation of vortices (cyclonic circulation). A ...
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### Potassum-Argon Dating and Proportions of Daughter Products in Potassium 40 Decay Channel

So Potassium 40 decays in such a way that roughly 89% of it becomes Calcium 40 and 11% of it becomes Argon 40. When they list these figures are they implying that after 1 half-life, of the 50% of the ...
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### Is this petrified wood? [closed]

I found this in my field 80% buried in the ground. I think it’s petrified wood but hoping for some help. Found in Milaca, Minnesota in what’s being used as a cow pasture. Very hard, solid, weighs 38.4 ...
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### wave speed is smaller than both horizontal wave speed and vertical wave speed?

I am new to GIS and just get the idea of slowness. I can understand why people need the slowness in GIS rather than just the reciprocal of velocity. However, I feel the definition of slowness is weird ...
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### When and where is the atmospheric greenhouse effect strongest?

Is the greenhouse effect stronger in the ice covered area or in the equator? Also is it stronger during winter or summer? I am thinking it is stronger in the Ice covered area and during winter because ...
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### What rock is this [closed]

So i found this rock in a creek in north Texas its hard and the shiny bits flake off if you touch it.Its hard to tell form the pic but the bits on it are silver a color , the rock looks like it was ...
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### Are those balsalt? Found in volcanoic field

My father came back from a volcanoic field called Wudalianchi in China and bought back these rocks. Both of them are dark grey and black with many holes. They are harder than nails and glass. I'm ...
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### If the accuracy of measurement of the earth's volume is not known, how can scientists assert that the earth is not expanding?

Volcanic eruptions, undersea earthquakes, fissures in the crust, meteoroid accumulation could all be seen as empirical evidence of expansion of the earth. Sink holes and other phenomena could be ...
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### How to calculate or find the compressional stress wave velocity, Cp for a rock

In Cunningham's paper, "The Kuz-Ram fragmentation model - 20 years on", he makes mention of compressional stress wave velocity, Cp. He only comments that the Cp of granite = 5.2 km/s. I using a ...
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### Do flights affect tides?

Can artificial satellite positions affect tides? on Space Exploration.SE asks if artificial satellites can affect tides, because they are a lot closer than our natural satellite, even though they are ...
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### Do cloud formations change depending on the season?

I'm currently working on some software for cloud masking, and thus far I have only been using satellite data as recent as spring (northern hemisphere). However, I'm wondering if cloud coverage or ...
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### Oscillating dew point throughout the year?

I was searching for the climate of Saudi Arabia and I noticed that the city of Abha (altitude of 7000 feet) has a "strange" behavior in its dew point, as numbeo suggests: https://www.numbeo.com/...
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### A few questions about the morphology and sediment dynamics of Wissant Bay (France)

Could someone please explain what exactly is shown on the following image? I have a few questions such as: How did the 'Banc à la Ligne' come about? (I know it has something to do with the fact that ...
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### Calculate GWP over arbitrary time

The GWP (Global warming potential) is calculated over a given time scale $T$ (20 or 100 years usually), defined as the ratio between the energy absorbed by a pulse of 1Kg of gas during time $T$ ...
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### How and when was the $\mathsf{CO_2}$ scrubbed when Earth was still primordial?

How and when was the $\mathsf{CO_2}$ removed in primordial Earth atmosphere? What is the main mechanism of this removal of $\mathsf{CO_2}$? Is it dissolving in water? Or rock weathering? Or was the ...
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### Do less trees equal less rain? [duplicate]

It is said the the Sahara desert was once a dense forest until it was cut. Do trees contribute to precipitation and less trees equal less rain locally?
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### Light and violet stone from Poland

Can anyone identify what is this? I live in Poland so it might narrow the possibilities.
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### What is the weather data covering the range of 359 to 360 degree

I downloaded a grib file of oceanography (Mean Wave Period) from ERA-Interim and the longitude values give the value at the points is 0,1, 2, 3....357, 358, 359 If I have geographical coordinates ...
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### Hi, is there good reference this raw earthquake data to covert into PGA, PGV and etc?

Is there good reference or software that these earthquake raw data will transform into strong ground motion such PGA, PGV and PGD. Thank you!