All Questions

95
votes
6answers
19k views

How can a storm drop 40 inches (1 metre) of rain?

Hurricane Harvey dumped more that 20 inches (500 mm) of rain over a large region, with 40+ (>1000 mm) in some spots... and much more expected. How is that possible? Does the atmosphere really hold ...
80
votes
6answers
20k views

What place on Earth is closest to the Sun?

What is the location on Earth that is closest to the Sun? I've seen this question asked many times, and answered in varied and contradictory ways: The most common answer is “the summit of Chimborazo ...
79
votes
2answers
24k views

Impossible or improbable? Hurricane crossing the equator

No known hurricane has ever crossed the equator. Hurricanes require the Coriolis force to develop and generally form at least 5° away from the equator since the Coriolis force is zero there. Are ...
70
votes
17answers
33k views

Are there any saltwater rivers on Earth?

I'm curious if there are any saltwater rivers on Earth. These would presumably arise if a saltwater lake had a river outlet to the ocean. However, all the saltwater lakes I looked at (Caspian Sea, ...
55
votes
5answers
329k views

Why does lightning strike from the ground-up?

The enlightening image below is of a lightning strike slowed down at 10,000 frames per second. It can be seen that the most intense flash produced from the lightening occurs in the direction from ...
50
votes
5answers
4k views

What started the US Dust Bowl of the 1930s, and could it happen again?

Most of us know about the Dust Bowl: the huge storms of dirt and dust that swept across America in the 1930's. But what I'm wondering is... What actually triggered the start of the Dust Bowl? Is it ...
48
votes
4answers
5k views

How much oil is created each year?

We all know that oil is an essentially nonrenewable resource over human time scales. However, I am currently working on an activity for high schoolers that teaches them to predict how long humans can ...
45
votes
5answers
29k views

How many trees would I have to plant to solve Global Warming?

According to Nasa, causes of the Earth's greenhouse effect include water vapor, carbon dioxide, methane, nitrous oxide, and CFCs. Carbon dioxide gets the most press, and NASA's page says: Carbon ...
44
votes
5answers
11k views

Why do snowflakes form into hexagonal structures?

Snowflakes are known to form into pretty hexagonal structures. The image below shows a variety of such structures that are possible (although by all means not an exhaustive list): What is the ...
43
votes
2answers
4k views

(How long) would Earth's atmosphere last without a global magnetic field?

The Earth's magnetic field provides an important protection against the solar wind (for example, see Wikipedia on Earth's magnetic field and references therein). Mars may have lost its atmosphere ...
41
votes
3answers
9k views

How do 'greenhouse gases' let heat in, but not let it out?

That honestly doesn't make any sense to me. How could heat pass through a gas one way but not the other? Its not like our upper atmostphere has a bunch of doors that can only open one way. To me, that ...
40
votes
10answers
24k views

Why is the pond in my backyard not frozen when it is -15 °C (5 °F) outside?

I am in O'Fallon, Missouri and today it is -15 °C (5 °F) outside. I was taught water freezes at 0 °C (32 °F). I could understand if it was exactly 0 °C (32 °F) that the water might not be turning to ...
40
votes
6answers
92k views

Are Richter-magnitude 10 earthquakes possible?

The largest earthquake since 1900 according to the United States Geological Survey (USGS) was Richter-9.5 magnitude quake in Chile in 1960. Are magnitude 10 earthquakes possible? If so, what is the ...
40
votes
2answers
5k views

Farthest point from the center of the Earth

At first glance, this seems like such a simple question of "What's the highest point on Earth". However, I also know that the Earth isn't perfectly round. So that "highest point" may be in a ...
39
votes
4answers
7k views

Are there any uncharted waters left on earth?

While reading about the ghost ship Jiang Seng I noticed that Wikipedia claimed it was drifting in uncharted waters in the Gulf of Carpentaria. I tried to find a primary source referencing uncharted ...
36
votes
3answers
29k views

Why is Earth's inner core solid?

I have never understood why earth's inner core is solid. Considering that the inner core is made of an iron-nickel alloy (melting point around 1350 C to 1600 C) and the temperature of the inner core ...
36
votes
3answers
34k views

What would be the temperature of earth if there was no atmosphere?

I do know that the atmosphere protects life on Earth by absorbing ultraviolet solar radiation, warming the surface through heat retention (greenhouse effect),and reducing temperature extremes between ...
36
votes
4answers
827 views

Why do the Siberian methane craters have smooth vertical walls?

I expect most of you have heard of this by now. All the news is about whether or not they were formed by the release of methane, but it is also mysterious to me why this crater has jagged edges but ...
35
votes
5answers
11k views

How is the mass of the Earth determined?

According to textbook knowledge, the mass of the Earth is about $6 × 10^{24}\,\mathrm{kg}$. How is this number determined when one cannot just weight the Earth using regular scales?
35
votes
2answers
842 views

Similarities between grand circulation solvers and mantle convection solvers

My impression is that both ocean grand circulation models (e.g. MITgcm), and Mantle Convection models (e.g. CitcomS), both use Navier-Stoke's as the governing equation. What are the other major ...
34
votes
6answers
8k views

Is the sea level rise unusual?

I'm discussing climate change with a friend who is a climate change denier, basically the argument is that looking at this graph, is not clear that something unusual is going on, so the sea level rise ...
34
votes
5answers
3k views

How do we know the asteroids formed at the same time as earth?

In continuation of the question Why is Earth's age given by dating meteorites rather than its own rocks?, what evidence do we have that the asteroids indeed formed at the same time as earth? Is there ...
34
votes
3answers
2k views

How would plate tectonics differ if Earth had no water?

Water plays a crucial role in plate tectonics by easing the brittle and ductile deformation of the Earth's lithosphere. Water lowers the Mohr-Coulomb for brittle fractures. During ductile deformation, ...
33
votes
9answers
22k views

What does a mm of rain mean?

Lots of people have explained it over many sites but I still can not confidently say that I know what it means when they say Hong Kong experienced 3mm of rainfall last Friday. Does it mean that 3mm ...
33
votes
3answers
13k views

Why is Earth's age given by dating meteorites rather than its own rocks?

Reading a course on Precambrian, I read that: Earth Age (around 4.5 billion years) is dated thanks to the meteorites hitting Earth during its formation rather than the inner materials composing the ...
33
votes
4answers
12k views

How can we determine the size and composition of Earth's inner core?

From Wikipedia: Earth's inner core is Earth's innermost part and is a primarily solid ball with a radius of about 1,220 km (760 mi). (This is about 70% of the Moon's radius.) It is believed to consist ...
32
votes
3answers
4k views

Why does Coriolis determine the rotation direction of a cyclone but not my drain?

It is a common misconception that Coriolis is responsible for the direction the water swirls down a toilet, tub or sink drain. E.g. does a toilet flush the other way in the southern hemisphere? (If ...
32
votes
3answers
2k views

How does anthropogenic heating affect global warming?

Anthropogenic-sourced greenhouse gases are commonly cited as the main source for human-caused climate change. However, something that I never see discussed is the actual heat produced by human ...
31
votes
4answers
5k views

How and why did the oceans form on Earth but not on other planets?

Earth is the only planet in our solar system that has copious amounts of water on it. Where did this water come from and why is there so much water on Earth compared to every other planet in the ...
30
votes
3answers
7k views

Why do felsic materials have lower melting points than mafic?

It is clear from Bowen's reaction series that more felsic minerals have lower melting points than mafic minerals. As far as I know, the same is true of quenched glasses. Felsics have a higher degree ...
30
votes
3answers
6k views

How would an icicle “grow” upwards?

The other day a friend of my dad's showed him a picture of an icicle that appeared to be "growing" upwards out of a crack in a sidewalk. There were no roofs, overhangs or vehicles parked near by... It ...
30
votes
2answers
981 views

How much of the current global warming is due to human influence?

Approximately what proportion of the global warming seen over the the last century is attributed to anthropogenic sources?
29
votes
4answers
3k views

How do weather models work?

We use different weather models all the time, such as the ECMWF and the GFS. These models are simply amazing to me. How do these models work? I know they have to take in various data points - what ...
29
votes
3answers
9k views

Is it true that earthquakes are not felt in a cave?

I took a tour of a cave in northern California last weekend. The tour guide asked us, "If an earthquake occurred, what would we feel in here?" My answer was, "fear," but she said we would feel ...
29
votes
2answers
6k views

Where on Earth is the magnetic field intensity stronger?

Are there places on Earth that have a strong magnetic field other than the magnetic north and south poles?
29
votes
4answers
34k views

Is it possible for rivers to freeze completely and stop flowing?

Is it possible for rivers to freeze completely in the winter and stop flowing? Are there known examples of this? If yes, how large can these rivers be and where does the water go? There are several ...
29
votes
4answers
30k views

Why is Earth's outer-core liquid?

The Earth's inner core is solid because despite the enormous temperature in this region, there is also enormous pressure there, which in turn raises the melting point of iron and nickel to a value ...
29
votes
2answers
41k views

At what humidity does it start to rain?

As far as I understand it is perfectly valid for air to have 100% humidity. At that point, all water can still exist in form of vapor, non-condensed. Does it immediately start to rain if humidity is >...
29
votes
1answer
2k views

What is the status of the Raymo & Ruddiman idea that Tibet cooled the Earth?

What is the current status of the Raymo & Ruddiman hypothesis that the uplift of the Tibetan Plateau during the Cenozoic cooled the Earth, resulting the current ice age(*)? cf. Raymo, M.E. and W....
28
votes
8answers
2k views

Is earthquake prediction possible?

After the Tohoku and East Coast quakes, I skimmed over several books discussing the validity of earthquake prediction as a discipline, yet found no significant breakthroughs. What should change in our ...
28
votes
6answers
86k views

How high must one be for the curvature of the earth to be visible to the eye?

I would like to ask that at what distance from the Earth's surface the curvature of the Earth is visible. What layer of the atmosphere is this? I've noticed that at the height of 9-12 Km (the view ...
28
votes
3answers
6k 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
438 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
6answers
5k views

How much will sea level rise if all the polar ice melts?

There are many movies about global warming, which say that melting of all polar ice would cause the whole world to suffer a huge flood. According my research (teachers, TV, Internet) people hold one ...
27
votes
4answers
837 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 ...
27
votes
2answers
13k 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
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 ...
27
votes
2answers
4k views

Is this XKCD comic an accurate timeline of the earth's average temperature?

Apologies for the length of the image, which I found at http://xkcd.com/1732/. I'm mostly interested in the temperature line itself, both the historical data and the forward projections. The reason ...
26
votes
2answers
7k 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
5k 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 ...

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