The Earth revolves around the Sun at a speed of about 18.5 miles/sec (30 km/sec) during this rotation, why the atmospheric wind is not felt by the earth?
Earth spins on its axis once in every 24-hour day. At Earth’s
equator, the speed of Earth’s spin is about 1,000 miles per hour (1,600
kph). The day-night has carried you around in a grand circle under the
stars every day of your life, and yet you don’t feel Earth spinning.
Why not? It’s because you and everything else – including Earth’s
oceans and atmosphere – are spinning along with the Earth at the same
constant speed.
Think about riding in a car or flying in a plane. As long as the
ride is going smoothly, you can almost convince yourself you’re not
moving. A jumbo jet flies at about 500 miles per hour (about 800 km per
hour), or about half as fast as the Earth spins at its equator. But,
while you’re riding on that jet, if you close your eyes, you don’t feel
like you’re moving at all. And when the flight attendant comes by and
pours coffee into your cup, the coffee doesn’t fly to the back of the
plane. That’s because the coffee, the cup and you are all moving at the
same rate as the plane.
Likewise, Earth is moving at a fixed
rate, and we’re all moving along with it, and that’s why we don’t feel
Earth’s spin. If Earth’s spin were suddenly to speed up or slow down,
you would definitely feel it.
The constant spin of the Earth had our ancestors pretty confused
about the true nature of the cosmos. They noticed that the stars, and
the sun and the moon, all appeared to move above the Earth. Because
they couldn’t feel Earth move, they logically interpreted this
observation to mean that Earth was stationary and “the heavens” moved
above us.
With the notable exception of the early Greek scientist Aristarchus,
who first proposed a heliocentric (sun-centered) model of the universe
hundreds of years B.C.E., the world’s great thinkers upheld the
geocentric (Earth-centered) idea of the cosmos for many centuries.
It wasn’t until the 16th Century that the heliocentric model of
Copernicus began to be discussed and understood. While not without
errors, Copernicus’ model eventually convinced the world that Earth spun
on its axis beneath the stars … and also moved in orbit around the sun.
Bottom
line: Why don’t we feel Earth rotating, or spinning, on its axis?
It’s because Earth spins steadily – and moves at a constant rate in
orbit around the sun – carrying you as a passenger right along with it.
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