The Earth's rotation is slowing down, very slowly but very surely. So what would happen if it slowed dramatically and finally stopped rotating around its axis completely but continued revolving around the sun and maintained the same angle of inclination around its axis? Witold Fraczek, writing for the Environmental Systems Research Institute (ESRI), posed this hypothetical question to demonstrate the capabilities of GIS to model such a possibility, using ArcGis "to perform complex raster analysis and volumetric computations and generate maps that visualize these results."
In an ArcUser Online article titled "If the Earth Stood Still: Modeling the Absence of Centrifugal Force," Fraczek states: "If the Earth's gravity alone was responsible for creating a new geography, the huge bulge of oceanic water- which is now about 8 km high at the equator- would migrate to where a stationary earth's gravity would be the strongest. This bulge is attributed to the centrifugal effect of Earth's spinning with a linear speed of 1,667 km/hour at the equator. The existing equatorial water bulge also inflates the ellipsoidal shape of the globe itself. If the Earth stood still, the oceans would gradually migrate toward the poles and cause land in the equatorial region to emerge. This would eventually result in a huge equatorial mega-continent and two large polar oceans. The line that delineates the areas that hydrologically contribute to one or the other ocean would follow the equator if the earth was a perfect ellipsoid. However, due to the significant relief of both the continents and the ocean floor, the hypothetical global divide between the areas that hydrologically contribute to one or another ocean deviates from the equator significantly. Analogous to the well-known U.S. Continental Divide, this would be the border separating two giant hemispherical watersheds of the new circumpolar oceans."
"The series of maps illustrating this article depict the intermittent stages during this migration of the Earth's oceans and changes in land extents, topographic elevation, and bathymetric depth caused by the decreasing speed of the Earth's rotation. These maps demonstrate the intermediate stages of transitional geography from a rotating to a stationary world. They show the effects of the gradual reduction of centrifugal force from its current level to none, leaving gravity as the only force controlling the ocean's extent."
To conclude, Fraczek comments: "The influence of the rate of the Earth's rotation has a dominant effect on the geometry of the globe, in terms of the globe's overall shape as well as the outline of the global ocean. The Earth's physical relief is only a secondary factor controlling the delineation of oceans. The slowdown of Earth's rotation will continue for 4 billion years- as long as we can imagine. The slowdown infinitesimally- but steadily- changes the globe's geometry and makes it dynamic. The net result of these dynamic adjustments is that the Earth is slowly becoming more and more like a sphere. However, it will take billions of years before the Earth stops spinning, and the gravitational equipotential creates a mean sea level that is a perfect sphere."
The probability for such an event is practically zero in the next few billion years. If the Earth stopped spinning suddenly, the atmosphere would still be in motion with the Earth's original 1100 mile per hour rotation speed at the equator. All of the land masses would be scoured clean of anything not attached to bedrock. This means rocks, topsoil, trees, buildings, your pet dog, and so on, would be swept away into the atmosphere.
If the process happened gradually over billions of years, the situation would be very different, and it is this possibility which is the most likely as the constant torquing of the Sun and Moon upon the Earth finally reaches it's conclusion. If the rotation period slowed to 1 rotation every 365 days a condition called 'sun synchronous', every spot in the Earth would have permanent daytime or nighttime all year long. This is similar to the situation on the Moon where for 2 weeks the front-side is illuminated by the Sun, and for 2 weeks the back side is illuminated. This situation for the Earth is not the condition of 'stopped' rotation, but it is as close as the laws of physics will let the Earth get.
If it stopped spinning completely... not even once every 365 days, you would get 1/2 year daylight and 1/2 year nighttime. During daytime for 6 months, the surface temperature would depend on your latitude, being far hotter that it is now at the equator than at the poles where the light rays are more slanted and heating efficiency is lower. This long-term temperature gradient would alter the atmospheric wind circulation pattern so that the air would move from the equator to the poles rather than in wind systems parallel to the equator like they are now. The yearly change in the Sun's position in the sky would now be just its seasonal motion up and down the sky towards the south due to the orbit of the Earth and its axial tilt. As you moved along constant lines of Earth latitude, you would see the elevation of the Sun increase or decrease in the sky just as we now see the elevation of the Sun change from a single point on the Earth's daily rotation.
For example, if you were at a latitude of +24 degrees North in the summer and at a longitude where the Sun was exactly overhead, it would slide gradually to the horizon as Fall approached, but since the Sun has moved 90 degrees in its orbit, it would now be due west. Then as we approach winter, you would now be located on the dark side of the Earth, and would have to travel in longitude to a location 180 degrees around the Earth to see the Sun 1/2 way up the sky because in the winter the Sun is 48 degrees south of its summer location in the sky. It's a little confusing, but if you use a globe of the Earth and orient it the right way, you can see how all this works out.
As for other effects, presumably the magnetic field of the Earth is generated by a dynamo effect that involves its rotation. If the Earth stopped rotating, it's magnetic field would no longer be regenerated and it would decay away to some low, residual value due to the very small component which is 'fossilized' in its iron-rich rocks. There would be no more 'northern lights' and the Van Allen radiation belts would probably vanish, as would our protection from cosmic rays and other high-energy particles. This is a significant bio-hazard.
"The series of maps illustrating this article depict the intermittent stages during this migration of the Earth's oceans and changes in land extents, topographic elevation, and bathymetric depth caused by the decreasing speed of the Earth's rotation. These maps demonstrate the intermediate stages of transitional geography from a rotating to a stationary world. They show the effects of the gradual reduction of centrifugal force from its current level to none, leaving gravity as the only force controlling the ocean's extent."To conclude, Fraczek comments: "The influence of the rate of the Earth's rotation has a dominant effect on the geometry of the globe, in terms of the globe's overall shape as well as the outline of the global ocean. The Earth's physical relief is only a secondary factor controlling the delineation of oceans. The slowdown of Earth's rotation will continue for 4 billion years- as long as we can imagine. The slowdown infinitesimally- but steadily- changes the globe's geometry and makes it dynamic. The net result of these dynamic adjustments is that the Earth is slowly becoming more and more like a sphere. However, it will take billions of years before the Earth stops spinning, and the gravitational equipotential creates a mean sea level that is a perfect sphere."
The probability for such an event is practically zero in the next few billion years. If the Earth stopped spinning suddenly, the atmosphere would still be in motion with the Earth's original 1100 mile per hour rotation speed at the equator. All of the land masses would be scoured clean of anything not attached to bedrock. This means rocks, topsoil, trees, buildings, your pet dog, and so on, would be swept away into the atmosphere.If the process happened gradually over billions of years, the situation would be very different, and it is this possibility which is the most likely as the constant torquing of the Sun and Moon upon the Earth finally reaches it's conclusion. If the rotation period slowed to 1 rotation every 365 days a condition called 'sun synchronous', every spot in the Earth would have permanent daytime or nighttime all year long. This is similar to the situation on the Moon where for 2 weeks the front-side is illuminated by the Sun, and for 2 weeks the back side is illuminated. This situation for the Earth is not the condition of 'stopped' rotation, but it is as close as the laws of physics will let the Earth get.
If it stopped spinning completely... not even once every 365 days, you would get 1/2 year daylight and 1/2 year nighttime. During daytime for 6 months, the surface temperature would depend on your latitude, being far hotter that it is now at the equator than at the poles where the light rays are more slanted and heating efficiency is lower. This long-term temperature gradient would alter the atmospheric wind circulation pattern so that the air would move from the equator to the poles rather than in wind systems parallel to the equator like they are now. The yearly change in the Sun's position in the sky would now be just its seasonal motion up and down the sky towards the south due to the orbit of the Earth and its axial tilt. As you moved along constant lines of Earth latitude, you would see the elevation of the Sun increase or decrease in the sky just as we now see the elevation of the Sun change from a single point on the Earth's daily rotation.
For example, if you were at a latitude of +24 degrees North in the summer and at a longitude where the Sun was exactly overhead, it would slide gradually to the horizon as Fall approached, but since the Sun has moved 90 degrees in its orbit, it would now be due west. Then as we approach winter, you would now be located on the dark side of the Earth, and would have to travel in longitude to a location 180 degrees around the Earth to see the Sun 1/2 way up the sky because in the winter the Sun is 48 degrees south of its summer location in the sky. It's a little confusing, but if you use a globe of the Earth and orient it the right way, you can see how all this works out.As for other effects, presumably the magnetic field of the Earth is generated by a dynamo effect that involves its rotation. If the Earth stopped rotating, it's magnetic field would no longer be regenerated and it would decay away to some low, residual value due to the very small component which is 'fossilized' in its iron-rich rocks. There would be no more 'northern lights' and the Van Allen radiation belts would probably vanish, as would our protection from cosmic rays and other high-energy particles. This is a significant bio-hazard.
Nice blog
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