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29
votes
4answers
1k views

Can pyroclastic flows cross water?

While reading the Wikipedia article on pyroclastic flows, I noticed that there's a section called 'Interaction with water'. This piqued my interest, as I was under the impression that lava generally ...
28
votes
10answers
13k views

Why does the salt in the oceans not sink to the bottom?

This is something that just occurred to me. If heavier elements sink, then how can the entire ocean be salty? Shouldn't the 'salt', because of its density, all sink to the bottom of the ocean? In ...
28
votes
3answers
7k views

Why are hail storms always brief?

It can rain all day, and it can snow for hours on end, but hail always seems to fall for short periods only. Why don't you get prolonged periods of hail?
28
votes
2answers
36k views

Why are there no hurricanes in the southern Atlantic basin?

We see tropical cyclones (going by different names e.g. hurricane, typhoon, cyclone) all over the tropics, but it seems that there are never any storms in the southern Atlantic. See this map of ...
28
votes
2answers
2k views

What sort of climate zones would be present if Earth was tilted like Uranus?

The three main climate zones on Earth are tropics, temperate and polar. Due to Earth's axial tilt, the three zones experience different seasonal patterns: The tropics experience 2 or 4 wet/dry ...
28
votes
2answers
498 views

What would it take to confirm or refute the Snowball Earth Hypothesis?

Since Harland's sedimentary work and Budyko's models in the 1960s, geologists have hypothesized that the Earth may once have been completely frozen. There are various lines of evidence for this event. ...
27
votes
7answers
33k views

Is a complete global flood physically possible on Earth?

Genesis 7:11-20 presents an account of a precipitation event which, in 40 days, submerges the entire surface of the earth: [On] the seventeenth day of the second month — on that day all the ...
27
votes
3answers
9k views

Antarctic and arctic meltwater is “bad” because it's dark, but why is transparent liquid on white stuff so dark?

The Washington Post's Antarctic heat wave melted 20 percent of an island’s snow cover in days, caused melt ponds to proliferate includes the figure below of meltwater ponds on top of snow/ice. The ...
27
votes
2answers
2k views

Would the Earth function the same spinning the other way?

Right, I saw a question about why the Earth spins counter clockwise, and it reminded me of something I would like to know the answer to. I watched a episode of Futurama. In this episode the Earth ...
27
votes
3answers
4k views

Equinoxes and solstices: start of the season or mid-season?

In the United States, the upcoming autumnal equinox is marked on most calendars as the "first day of autumn." Similarly the solstices are commonly called the "first day of summer" and "first day of ...
27
votes
2answers
16k views

Why is Europe warmer than North America at similar latitudes?

Traditionally it has thought to be the Gulf Stream. But other researchers, like Richard Seager and Tapio Schneider, propose different arguments as to why. How much of a role does the Gulf Stream ...
27
votes
2answers
3k views

Why does El Niño only exist in the Pacific Ocean and not the Atlantic/Indian Oceans?

El Niño is associated with the weakening of the ‘normal’ pressure/temperature gradients between the western and eastern Pacific Oceans. My question is this: why does it only exist in the Pacific ...
26
votes
7answers
11k views

Could the Earth's core lose its heat?

Will all the drilling and digging to use the Earth's natural heat as geothermal energy affect the Earth's core, causing it to cool down? If so, would it result in an ice age? If not, how does the ...
26
votes
2answers
8k views

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 ...
26
votes
2answers
6k views

Is there a name for the great circle where latitude and longitude are equal?

Is there a name for the great circle where latitude and longitude are equal? I have attempted a google search but only the equator and the prime meridian are defined in the sources I can find. ( It is ...
26
votes
5answers
19k views

Why was the initial theory of plate tectonics so controversial?

I have been set the task of researching plate tectonics, specifically: "Why was its discovery so important in its time and controversial?" I do not need a long answer, although more detail is always ...
26
votes
3answers
5k views

Why is Olympus Mons the largest volcano in the whole solar system?

Why is it that the volcanoes found in the Tharsis Montes region near the Martian equator, (one of which is Olympus Mons) so much larger than those found on Earth. In comparison, Hawaii's Mauna Loa, ...
26
votes
2answers
8k views

Is there sand in Antarctica?

There's a song "Blizzard's Never Seen the Desert's Sand". Given Antarctica is a desert, someone questioned the title's validity. BUT is there sand in Antarctica? I'd imagine yes as it's a pretty ...
26
votes
4answers
7k views

Why is relative sea-level falling in Hudson Bay?

Why is the sea level in Hudson Bay decreasing so much? Hudson Bay is pretty far up north, much closer to glaciers. Would it make sense for it to recede at this level with sources of fresh water ...
26
votes
4answers
4k views

Could the extraction of energy by wind turbines be harmful to the environment?

Wind turbines work by converting some of the energy from wind to electrical energy. Is it possible to have too many turbines, leading to them removing too much energy from the wind? I'm not an ...
26
votes
1answer
3k views

Why does glacier ice look blue?

The color of the ice observed in glaciers, icebergs and crevasses is often blue. However, ice cubes and industrial ice blocks are perfectly transparent or white if not. So. Why does glacier ice look ...
26
votes
1answer
824 views

How can the following equations for meandering rivers be theoretically obtained?

It has been observed that the shape of a meandering river is roughly circular, not sinusoidal (Leopold and Wolman 1960). It has also been observed that the following mathematical relationships tends ...
25
votes
4answers
2k views

Can mining trigger earthquakes?

Are earthquakes more common in mining regions than they would otherwise be? e.g. is the frequency of earthquakes in those regions different when mining is occurring than when it is not? I am ...
25
votes
5answers
5k views

During the “Ice Ages” or “Snowball Earth” times, where was all the energy?

We often seem to accept the idea that there were periods of time in which the entire surface of Earth was frozen, for the most part. This implies that there were periods of time in which the entire ...
25
votes
4answers
12k views

What is the origin of the dominant atmospheric nitrogen content in Earth's atmosphere?

Comparing the atmospheric compositions of Earth with our nearest neighbours: As the table shows, the Earth's atmospheric nitrogen concentration is 78%, compared to 3.8% for Venus and 2.7% for Mars ...
25
votes
2answers
2k views

What is the steepest surface that can hold snow?

I know it depends on the type of snow (dry or wet) and the rougness of the surface. I'm looking for an approximate rule of thumb answer. Assuming a reasonably smooth surface, at what angle it's likely ...
25
votes
3answers
37k views

Why is Earth's inner core made of an iron-nickel alloy?

This question has puzzled me for a while. I know that earth's mantle is made of different minerals, metals and rocks etc. and that has always made complete sense to me. But why is the inner core made ...
25
votes
3answers
28k views

Why are alpine river water green - blue?

I recently visited Slovenia where I saw several rivers with a strong blue-green color. Here is an example from one of the tributaries of the Soča river near Kobarid. The locals refer to it as an "...
25
votes
1answer
9k views

How much of a mountain is below the surface?

Is there some kind of math rule for how much does a mountain extend (depth) below the surface? I found an article like this http://www.livescience.com/6595-depth-himalayan-mountain-roots-revealed....
25
votes
1answer
41k views

What is responsible for the underwater waterfall illusion of Mauritius Island?

From an aerial view just off the island of Mauritius, there is what appears be an underwater waterfall. The picture below illustrates this visual phenomenon: The image can also be seen from the ...
25
votes
1answer
674 views

How much have global GPP and biomass changed over Earth's history?

I'm curious about how much is known about this topic: how much has the total amount of life on Earth changed over the 4 billion years or so that it has existed on this planet? Are there estimates of ...
25
votes
2answers
786 views

Why do some planets have lots of $\mathrm{N_2}$ and others none?

Earth, Titan and Venus all have large amounts of $\mathrm{N_2}$ in their atmospheres. (In the case of Venus it's a small proportion, but Venus' atmosphere is very thick, and the total mass of $\mathrm{...
24
votes
4answers
6k views

Why is the temperature *still* rising?

2015 is the hottest year on record, and the average temperature continues to rise. I don't understand why this continues, as (over the past twenty years) so much work was put into reducing Global ...
24
votes
2answers
5k views

How do oases form in the middle of the desert?

I am wondering if there are any theories about the formation of oases, and I am also curious about why an oasis can even last for a very long period of time. I have heard that fresh water exists on ...
24
votes
3answers
17k views

Why is there a seasonal cycle to the amount of CO2 in the atmosphere?

I'm doing some homework on the increase of $\mathrm{CO}_2$ in the atmosphere. On one of the graphs it shows the amount of $\mathrm{CO}_2$ peaks in May and has a low in November. Why is this? Shouldn't ...
24
votes
3answers
8k views

What do weather forecasters mean when they say “50% chance of rain”?

What do weather forecasters mean when they say "50% chance of rain"? Even more confusing: weather report often says something like "30% chance of rain. >10mm", then the next day "70% chance of rain &...
24
votes
1answer
4k views

What's causing this high SO2 concentrations in Kazakhstan?

I was using this website for weather conditions around the world called Ventusky (https://www.ventusky.com/) and one of its features allows you to view SO2 concentration. I stumbled upon this high ...
24
votes
2answers
2k views

What is the cause of the jet streams?

Jet streams are fast-flowing currents of air in our earth's atmosphere. An enormous amount of energy is necessary to keep a jet stream going. Where does this come from and why?
24
votes
2answers
4k views

Natural nuclear explosions

I'm aware of the Oklo reactor and other natural nuclear fission reactors, in which geological processes can lead to the formation of a sustained, self-regulating uranium fission reactor. Is it also ...
24
votes
1answer
3k views

What were the tallest mountain ranges in Earth's geological past?

There have been numerous episodes of mountain building in Earth's geological history, particularly through the super-continent cycle. Many mountains and mountain ranges have been eroded, as mentioned ...
24
votes
1answer
727 views

Why did the Laki eruption of 1783 produce so much fluorine?

The Laki fissure eruption of 1783/4 in Iceland was not particularly large or explosive, but it is infamous for the large quantities of fluorine (or hydrofluoric acid) and SO2 that it produced, and the ...
24
votes
0answers
439 views

Is it possible for a sting jet to form over a continental landmass?

Sting jets are thought to be responsible for some of the most damaging winds associated with extratropical cyclones in the mid-latitudes. So far they have only been confirmed in the European region, ...
23
votes
5answers
26k views

Is the color of the sky the same everywhere on earth?

Is the color of the sky at noon (local time) in, say, NY, Buenos Aires, London, Nairobi, Sydney, New Delhi and Tokyo the same? I choose the specific time of noon to exclude the twilight colors of the ...
23
votes
3answers
57k views

How do I convert specific humidity to relative humidity?

How do I convert specific humidity to relative humidity? What variables are needed (e.g. air temperature, pressure, etc.)?
23
votes
7answers
11k views

Does human body temperature impact climate change?

The human body temperature is about 37 °C (99 °F), so as the population increases does this cause the Earth's temperature to rise?
23
votes
4answers
2k views

Does the strength of Earth's magnetic field influence its climate?

The strength and orientation of Earth's magnetic field varies with time. Does this variation of the magnetic field have any influence upon climate? For example, is there any correlation between ice ...
23
votes
2answers
17k views

Why do crystals, like quartz and diamonds, form in different colors?

Some crystals, like quartz and diamonds, form in a variety of different colors. For example, quartz can be clear, 'foggy', pink, yellow, and even blue. What happens during the crystal's formation to ...
23
votes
3answers
874 views

How good were climate models of the 1990s at predicting the global temperature trends of the 2000s/2010s?

Was there a significant bias between the ensemble of climate models and the long-term temperature trends? What about spatial patterns?
23
votes
1answer
18k views

Do tornadoes have eyes?

In the movie Into the Storm (2014) near the end, storm chaser Pete sees the eye of a massive tornado. In 1928 (real life), Will Keller was in his barn when a huge tornado passed through. He reported ...
23
votes
2answers
868 views

Is climate chaotic?

The atmosphere is a highly dynamical system, and exhibits many chaotical features. An operational weather forecasting model tries to model an initial value problem, in fact one of the most famous ...

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