33
votes
In the northern hemisphere summer, why are places in the north cooler than those in the south?
The image below (apparently from "physicalgeography.net" is somewhat instructive:
Notice that even in the middle of summer, India (at about 30 °N) still gets slightly more sun than the ...
- 697
29
votes
Why clouds are not moving in NASA's video of the Moon passing in front of the Earth?
The clouds can be seen moving but of course it's subtle at first glance.
Frame 16:
Frame 20:
- 391
28
votes
Accepted
Would the Earth function the same spinning the other way?
That would have many consequences. For example the Coriolis force would change the sign. Thus wind around pressure systems would switch the direction from north and south hemisphere, but also the ...
- 1,662
27
votes
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Why clouds are not moving in NASA's video of the Moon passing in front of the Earth?
They are moving, but not fast enough to notice at the distance shown. From the NASA page:
These images were taken between 3:50 p.m. and 8:45 p.m. EDT on July 16, showing the moon moving over the ...
- 11.1k
24
votes
Accepted
What is the fastest the Earth has ever spun?
The speed of rotation of Earth is controlled by its angular momentum. And the conservation of angular momentum is a very serious law of physics (perhaps even stricter than conservation of mass). So in ...
- 17k
23
votes
Would the Earth function the same spinning the other way?
Depending on the assumptions you make, the Moon would suddenly have a retrograde orbit. If the moon had a retrograde orbit, it would have tremendous consequences. Retrograde orbits tend to become less ...
- 331
19
votes
Accepted
What geophysical events can (temporarily) increase the Earth's rate of rotation?
TL;DR
The Earth's rotational angular momentum is indeed being transferred to the Moon's orbit. However, this is a very slow process that is barely noticeable even over the course of hundreds of years. ...
- 20k
18
votes
Accepted
Is it true that distance between earth and sun is closer in winter season (January) and farther in summer season in the Northern Hemisphere?
Yes, it's true (in the northern hemisphere). The small eccentricity of the Earth's orbit is not anywhere close to a key driver in the seasons. The key driver of the seasons is the Earth's obliquity. ...
- 20k
18
votes
Accepted
Will the Earth ever stop rotating?
The short answer is "Probably Yes".
The longer answer is that it is debatable whether Earth's rotation will become tidally locked to the moon due to tidal drag, at which point it will not be rotating ...
- 502
14
votes
Accepted
Effect on sea level if the Earth stopped rotating
Let's assume that the earth didn't suddenly stop spinning (because intertia and conservation of angular momentum would do all sorts of "interesting" things that are deserving of a What-If answer), and ...
- 5,805
12
votes
Accepted
Does the geographic North Pole move?
Yes, it's called polar motion.
The rotational pole moves continuously, as you can see from the right-hand side of this figure (below) by the Earth Orientation Centre (EOC) and the International Earth ...
- 10.8k
12
votes
In the northern hemisphere summer, why are places in the north cooler than those in the south?
Hours of sunlight are not the only factor that determines insolation (solar energy at the surface).
Thought experiment: spread a bed sheet on the floor, switch the lights off, and shine a flashlight ...
- 221
11
votes
Accepted
How fast does the Earth's inner-core spin?
Roughly once per day, but a tiny bit faster. As the website for Columbia University's Lamont-Doherty Earth Observatory says:
The inner core rotates in the same direction as the Earth and slightly ...
- 3,028
11
votes
Why clouds are not moving in NASA's video of the Moon passing in front of the Earth?
The image is real, and the clouds are moving, they just move slow, as clouds do.
The unnatural appearance arise because they are taken by DSCOVR at an extraordinarily large distance, from a place ...
- 17k
10
votes
Why do we say Earth rotates from west to east?
Your confusion arise from the definition of East and West hemispheres. That's an arbitrary and confusing definition. Because East and West are relative directions. Meaning they depend on the position ...
- 17k
10
votes
Accepted
Changes in Earth's orbital and rotation speeds
The Earth moves faster around the Sun when it is near its perihelion (the closest point of its orbit to the Sun). And it moves slower when it is further away (aphelion), just as Kepler realized quite ...
- 17k
9
votes
Effect on sea level if the Earth stopped rotating
This is covered in an episode of the National Geographic TV series Aftermath called "When The Earth Stops Spinning". It's also covered by "If the Earth Stood Still: Modeling the absence of ...
- 191
9
votes
How are Earth's rotational changes due to large earthquakes calculated?
Earthquakes, specially those at subduction zones, result in redistribution of mass (as one plate slides on top of the other). This change in distribution of mass causes changes in gravitational field ...
- 2,361
9
votes
Accepted
why we don't have solar eclipse every month?
The moon's orbit is at a slight angle from the plane of earth's orbit around the sun, so it doesn't always hit the right spot, as described on NASA's Total Solar Eclipse 2017 site:
Eclipses only ...
- 2,803
8
votes
Accepted
Could Earth have had a greater axial tilt?
There is no evidence that Earth had a much greater axial tilt so long ago. To my knowledge, the evidence for changes in the axial tilt of the Earth is based on ocean sediment cores (see http://en....
- 12.7k
8
votes
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Why is this "independently reproducible proof of non-curvature" wrong?
The biggest flaw I see in a cursory look at this work is failure to compensate for atmospheric refraction. Density varies in the atmosphere enough that the refractive index varies. At low angles ...
- 13.9k
8
votes
How to measure the cycles of earth moving/rotation?
In theory, if the Earth was a solid object, the Chandler wobble would be easy to understand. It's simply a result of the polhode rolling without slipping on the herpolhode lying in the invariable ...
- 20k
7
votes
Why do we say Earth rotates from west to east?
Imagine you can fly ignoring wind, gravitation and other forces. You are exactly on the rotation axis looking down the Earth on its North side. You'll see the Earth turning counter-clockwise. But If ...
7
votes
Accepted
Which are the equations needed to calculate how much moving Earth's water with dams would change Earth's rotation speed?
You need to calculate the change in the moment of inertia of the Earth and use conservation of angular momentum. In the case of eg. a large dam, (most of) the water will ultimately come from the sea, ...
- 2,269
6
votes
Why do we say Earth rotates from west to east?
The Earth rotates from west to east or counter-clockwise. You can do simple experiment. put your face towards the polar star and stretch your hands. Your head shows North (towards polar star) and your ...
6
votes
Is it true that distance between earth and sun is closer in winter season (January) and farther in summer season in the Northern Hemisphere?
David's answer is correct, but I wanted to elaborate a bit further.
The Earth's axis is tilted about $23.5^\circ$ from being perpendicular to the plane of its orbit (as David mentioned, 'obliquity' ...
- 163
6
votes
Accepted
How are Earth's rotational changes due to large earthquakes calculated?
Changes in the Earth's rate of rotation is measured by the International Earth Rotation and Reference Systems Service (IERS) using observational techniques. They publish daily the rate and orientation ...
- 3,780
5
votes
Will the Earth ever stop rotating?
Strictly speaking, the Earth will never cease to rotate in the technical sense... not while Earth is intact at least. No matter what the Earth might eventually become tidally locked with, whether the ...
- 51
5
votes
What would be the impact on tides if the earth had no tilt?
A simple way to estimate the implications is to simplify the problem. If the orbits of Earth, Sun and Moon were circular and in the same plane, and the Earth had no tilt, the only remaining tidal ...
- 14.7k
5
votes
Accepted
Are the length of seasons the same globally?
As has been noted in a comment, it depends on how you define seasons (see https://earthscience.stackexchange.com/a/2603/111).
If seasons are defined in astronomical terms, then they have the same ...
- 5,805
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