Which terms refer to major subsystems of earth's physical systems?

The majpr systems of the earth are atmosphere, biosphere, hydrosphere and lithosphere. Subsystems would be things like of the hydrosphere the water cycle ie ocean water evaporating and forming clouds and then passing over mountains and precipitating as fresh water and then having run-off forming creeks and rivers and then returning to the sea. A subsystem of the lithosphere would be the rock cycle of how sediments are transported and deposited and converted to sedimentary rock and then perhaps heated and with pressure become metamorphic rocks and then the movement of the tectonic plates and subduction would result in igneous rocks being formed,

This is all you, but i can give you some topics that you could try. if it rained when you want to do something outdoors, it 'limits' that human activity. maybe you want to do an experiment that goes throughout the whole year and you have to have above freezing the entire year. this 'limits' your activity. i thought of those just off of the top of my head. something that gets to me that might be getting to you is you are thinking too hard about what to do. think simply, and if it is too simple, then bump it up just a little bit.