What is the principle of One Piece weather bar in Nami? Can it be done in reality?

The principle of weather bar in Nami is actually the same as that of clouds, rain and thunder in nature. But that's animation. It is impossible to control the weather in a small area with only a small stick. In the real world, it can't be done by current technology alone.

If you want to change the weather, the most important thing is clouds. Without clouds as a carrier, it is nonsense to want to form thunder, rain, hail and snow. And the formation of the cloud is not like Nami, just take two short sticks and you can turn around.

There are two most necessary conditions for the formation of clouds: first, there is sufficient water vapor, and second, there is cold air that condenses water vapor. Both conditions are indispensable. High-temperature steam liquefies into small water droplets when it is cold. Nami often creates dark clouds and lightning at low altitude and indoors, which is absolutely necessary for the plot and cannot be formed in the real world.

The formation of lightning is an electrostatic phenomenon caused by the mutual friction and decomposition of water molecules in the sky. Popular point lightning is a violent discharge phenomenon in the atmosphere. Moreover, lightning often occurs in thunderstorm weather, when the air humidity is high and there are enough water molecules in the clouds to rub against each other, so lightning can be formed.