Why does planet earth have the weather it does
Very simply put, its all down to the fact that the sun does not heat up the earth evenly ....
Imagine a static Earth with no land, covered just by water.. The equator of the planet would be nearer the sun and so would be hotter than the rest of the planet ;in particular the poles. This in effect means that the poles north and south would be colder than the equator.
Due to the convection of air, Hot air would rise from the equator and cold air from either pole would be pulled in to the equator. This would set up a three dimensional basic circulation of air rising at equator and moving to the poles and sinking whereby it would circulate back to the equator.
Lets now examine an earth that's similar to ours and that is rotating in space on its own axis. This will cause the coriolis effect to take effect.All movement in the northern hemisphere will be diverted to the right whilst in the southern hemisphere all movement will be diverted left. With this effect, this ensures the creation of six wind bands from pole to pole, three in northern Hemisphere and 3 in the southern hemisphere. Air at about 60? north and south is continually rising and spiralling upwards. This constant sucking of air away from surface will reduce the surface pressure locally, which is why formation of low pressure systems is normally between 40? and 70 ?.However the air around 30? north and south is always sinking, continually trying to pump more air into the surface layers and so increasing the surface pressure. We now have a rotating water covered planet with a low and high pressure belts around the surface and an expected circulation pattern
When we consider how such a planet is affected by the inclination of the planet around the sun, at a particular time around the year. The earth rotates at 23.5 ? around the sun. Depending on which pole is nearer to the sun, one hemisphere is warmer than the other. Due to this tilting, distance between the poles and the sun varies much more throughout the year than the distance between the equator and the sun. This causes wild swings in the polar temperatures nu none in equatorial ones. For example in February ,the north pole is much colder than the equator approx 70?.However in August the north pole is warmer and the equator is the same, so theres only a small difference in summer. As air movement is caused by uneven heating, this movement of winds will be increased more in the winter. And so The bigger lows will be created in winter
Finally lets look at a spinning earth around the sun, covered in water and land and inclined at 23.5? as our earth currently does. land and water react differently to the sun, they have different specific heat capacities, namely water has larger heat capacity.
It takes a lot longer to heat up and cool down. While the temperature of the lands swings many tens of degrees from winter to summer, the sea stays at a more continuous average temperature. In the summer pressure over the land is lower than pressure over the sea as over the land , the air heats up and rises more. Generally speaking in around 30? highs tend to be over the sea leaving low pressures over the land. The reverse happens in winter with the low pressure over the sea and highs over the land
One more thing to remember is the existence of more land in northern hemisphere than the southern, this too has an affect which causes an increase in the east west pressure variation
Taking all the above in to account, we can see something that is very similar to the weather patterns that we actually get on earth..