Meteorological vs astronomical seasons

In the field of meteorology the year is divided into 4 seasons following the climate: winter is made out from the coldest months of the year (Dicember, January and February); summer consists in the hottest months (June, July and August). The seasons in between these two are spring (March, April and May) and fall (September, October, November). These are the meteorological seasons.

So what’s the difference with the astronomical seasons?

Well, the year can also be divided following the movements of the Earth, the tilt of the Earth’s axis, and its position around the Sun. The Earth’s orbit is not a perfect circle, but seasons are not a consequence of how far or near the Earth is to the Sun. The distance has no effect on our weather or our seasons. So why do we have different seasons?
The solution lies behind the Earth’s axis. It’s is an imaginary pole going right through the center of Earth from “top” to “bottom.” Earth spins around this pole, making one complete turn each day. That is why we have day and night, and why every part of Earth’s surface gets some of each.
So, we have seasons on Earth because its axis doesn’t stand up straight.

Equinox and Solstice dipend on this: when the North Pole tilts toward the sun (around June) summer starts for the Northern Hemisphere; when the South Pole tilts toward the sun (around December) the winter starts for the Northern Hemisphere.

It is summer in June in the Northern Hemisphere because the sun’s rays hit that part of Earth more directly than at any other time of the year. It is winter in December in the Northern Hemisphere, because that is when it is the South Pole’s turn to be tilted toward the sun. Since this movement is not stable, the moment of Equinoxes and Solstices vary each year.
From the winter solstice the winter begins, spring starts from the spring equinox, summer starts from the summer solstice, autumn starts from the fall equinox.