Today I want to comment on a process that happens on the earth and is very interesting, the so-called Hadley cell.
The Hadley cell is the set of convection currents that pass in the atmosphere of our planet due to sunlight, the rotation of the Earth and the water existing in the atmosphere and seas.
As you know, a convection current occurs when there is a temperature difference in a material. As you will know (quickly), too, temperature is an element that varies the energy of atoms and is able to modify the density of groups of these by increasing their energy and therefore their vibration.
Once we know and remember this, we know that the denser materials, by gravity, tend to be under the less dense materials, matter of weights. So a convection current is nothing more than a density gradient that causes the material to move between two layers. If we make the lower layer of a material warm, it decreases its density by positioning itself above the dense zone and, if it is there, it cools, it will increase its density lowering. Continuing and repeating this process (heats, rises, cools, low) we have a convection current. Come on, what happens in the pots when we put water and put them on the fire.
The Hadley cell are the different convection currents on Earth that move the atmosphere and cause different types of moisture on Earth.
Let’s add another definition. Hot air is capable of containing more water than cold air. That is, hot air is more humid than cold air. This is easy to understand knowing that water has a very high density of temperature absorption which causes it to cool and condense more easily than, for example, nitrogen or oxygen (fundamental components of our atmosphere). For this reason the cold air condenses more precipitating water and, therefore, the air itself has less evaporated water. The so-called adiabatic cooling of all life.
The terrestrial climate is largely conditioned by Hadley cells because, as I said, the rotation and coriolis effect makes these cells a concrete size (actually about 30 degrees of arc). The sea and light make different cells have different temperatures and that the Earth has different climates depending on which cell we find.
Now, between cell and cell there are some very interesting points for the climatology called “zones of convergence”. In these zones they create strong currents of winds (in fact is where they are the famous jet stream) causing that in the terrestrial surface Where this happens may have somewhat “extreme” climates. Thus, in the tropical zone (the zone of tropical convergence) we have many rains, in the subtropical zone it does not rain since they are ascending hot winds all and they are the deserts or in the Arctic zone, it is cold wind that “falls” with much humidity .
The importance of cells as entities that control the climatology of the planet is basic. Unfortunately with the climate change that we are causing, although the light that reaches us remains the same, these cells are being modified in size and strength causing the winds to change and the currents also. This is forcing the planet to change global temperatures by not being homogenized as before and is giving rise to these sudden changes in, especially and as you can see, hurricanes, storms and rains since, as we have said, the cells control to a great extent these phenomena.