If I open the windows in my room, which has AC turned on and it’s cool in the summer, it will quickly become as hot as it is outside, why isn’t it happening around the globe?
In: Physics
Because air does not move as fast as the Earth rotates.
Consider a stupidly simple setup –
If air to be moving at 500 km/h (imagine the wind), it would take about 3 days for it to go around the Earth. In those 3 days, the Earth has rotated thrice…so the heating from the Sun has changed it direction three times. So before the air temperature cam equalize the heating has shifted to another side.
Its like you keep moving your heater or AC to different parts of the room before the air can actually circulate and reach a constant temperature all over.
Of course, air doesnt move at 500 km/h , and a lot more complicated stuff happens – land heats up faster than the sea, the earth is tilted depending on season etc. All this makes it even mlre impossible to reach a constant temperature .
ELI15: This is why whether is a ‘dynamic/chaotic’ system. Energy us being fed to the system ‘anisotropically’ faster than the system can ‘equilibrate or reach a steady state’.
Your room is a small. Maybe 10 metres across. Even air moving at 10 metres/h (your walking speed is about 5000 m/h) would completely exchange with the outside within an hour. But even it doesnt really have a constant temperature if AC / heater is on. The air close to the device is hotter/ cooler. It just moves around quickly enough for you to not notice the tiny difference in temperature if you open the room.
Adding to the other explanations here: The Sunshine slants down at different angles as you go towards or away from the Equator.
So, in addition to “it’s day here/night there, and the atmosphere is mostly rotating about as fast as the surface is”, add “the Sun is shining straight down _here_ (this is always somewhere within 23 degrees of the equator, and right on it at spring/fall equinox) and shining very slanted at the Poles – never more than 23 degrees high in the sky, and half the year not at all”.
So sunshine heats the Earth up pretty unevenly, which gets transferred to the local atmosphere to affect its temperature.
Plus which, conduction (heat transfer between things touching, like pieces of atmosphere, or Earth’s surface and atmosphere touching it) and convection (heat being carried by the air or water as it moves) are local, not global, and take time to spread heat from one locale to another. Jet steams can make convection go faster, but never instantly.
–Dave, soooomewhere, oooover the raaaainbow
The very short answer is because Earth is not a static system. Between it’s orbit (closer and further from the sun in an ellipse), rotation and tilt (daily cyclic energy input as well as the Coriolis effect of the planet dragging the air along with it ), and even the moon’s tug there are plenty of forces constantly acting to slosh things around. More importantly, the sun is adding an enormous amount of energy to the system…but only on half the globe at once. This daily heating and cooling – thus cyclic expansion, contraction, and thermal updrafts cause most of what we consider weather and climate. Even if there was no sun suddenly, there isn’t enough time in half a day to get the world’s temperature differentials to settle out and become homogeneous.
Imagine you have a heater in one side of your house and a cooling machine on the other side. You won’t reach an equilibrium. It’ll be hot on one side and cold on the other and warm in the middle.
The earth has a tilt causing half to recieve more sun therefore heating it, making it summer, and the other half to be colder making it winter. U
It does always try to reach equilibrium. Water is one of the major variable regulators. The hotter the world gets, the more hurricanes we get, because they are the end results of dissipating heat.
We are getting hotter because of deforestation for monoculture agriculture. I can elaborate a lot more on this if requested.
The sun is constantly changing position relative to the Earth and heating up different areas. Air also does not mix very well compared to liquids, so you get warm air constantly rising and cooler air taking it’s place, only to be warmed up by the ground and cycle up. Basically, conditions are changing faster than the air has a chance to mix.
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