In my opinion, LHP and RHP cannot be defined abstractly, in terms of just one aspect of the principles or aims of a particular path. Instead, I regard LHP and RHP as groupings that have evolved spontaneously, and whose meaning is mainly social and historical.
The cold plate causes the moisture in the warm air, which is inside the jar to condense and form water droplets. This is the same thing that happens in the atmosphere. Warm, moist air rises and meets colder air high in the atmosphere. The water vapor condenses and forms precipitation that falls to the ground.
We have made rain clouds in a jar a few times in the past, and the girls love this activity more each time we revisit it. Rain Clouds in a Jar. Before making rain clouds in a jar discuss how it rains and what causes rain to form. Review where rain comes from and the process of how rain clouds form. The girls and I Googled a few questions and discussed some of the information we found. We also read a few weather related books.