The Day The Earth Stands Still
A year is 365 days, one full orbit around the Sun. A day is one full turn on the Earth's rotational axis. So what would happen if the Earth's rotation just suddenly stopped? If the Earth stood still suddenly, everything not attached to the crust of the Earth would just be swept up into the atmosphere. Nothing would be able to be maintained on the surface of the Earth, what keeps us grounded will be gone.
The chances of this happening are practically zero so I wouldn't panic. The laws of physics don't allow for the Earth's rotation to suddenly stop given the orbit around the sun or the moon's orbit around the Earth.
If the Earth stood still following a gradual process of slowing the situation would be very different. On the day the Earth stands still, one half of the Earth would experience permanent day light and the other half would have permanent night time. This would repeat on 6 month cycles given the Earth orbiting the sun without spinning.
This is similar to the moon cycles, 2 weeks one half is illuminated on one side and the other 2 weeks the same side will not be.
Over time the surface temperature will become much hotter at the equator than it would be nearer the poles. The light rays would have more of a slant and the heating efficiency wouldn't be as powerful as it would be now.
On the day the Earth stands still, the Sun wouldn't rise in the east and set in the west as the world isn't turning anymore. The sun would just rise up and down given your position on the Earth. If the Sun doesn't stand still, it would continue in its own orbit around the centre of the galaxy.
If you were in a position that the sun was directly overhead in summertime when the Earth stood still, it wouldn't exactly stay there forever. The sun would move slowly towards the horizon as Autumn approached. As we approach winter, you would find yourself on the dark side of the Earth.
The day the Earth stands still means that nobody will see an Aurora again. I explained in a previous post that the solar rays and charged particles in the atmosphere interact to give us the light shows we see today. This is further caused by the Earth's magnetic field.
Our magnetic field repels deadly solar rays, charged particles and gamma ray bursts from hitting the Earth. Solar flares and other phenomena can get through and have done, but without the magnetic field, the Earth would be totally on edge.
Over time the solar rays would strip the Earth of its atmosphere and the guardian shield of the human race would slowly leave us to fend for ourselves. Unless the human race finds a way to overcome solar radiation, it would cause extinction. How long it would take for the atmosphere to vanish would be a guess.
The day the Earth stands still won't mean it will be completely still. The Earth will still orbit the Sun. The laws of physics won't allow space and time to stop everything orbiting simultaneously.
If you want a snap shot of what things will be like when the Earth stands still, look at Mars. A planet brimming with water, possible foliage and life was destroyed by the sun. Yes Mars still turns but very slowly to allow the solar rays to destroy the atmosphere quicker than the planet turns to protect itself.