Why does people say that the water cycle is a closed system?

Question

If water enters the atmosphere in tons a month with meteors, and the sun`s electrons break water molucules into H and O in the upper atmosphere(not sure about the chemistry)

Then the water cylcle isnt a closed system! I had this wrong in so many test and I cant explain this to the teacher, is my saying correct?

Answer 1

The water cycle is a closed system because "water" comes in three forms or phases: solid, liquid and gas.  The water molecules that exist in air as vapor (or gas) can condense and become droplets big enough and heavy enough to fall and be seen in their liquid or solid state (dew, rain, ice, snow, etc.).   Water can change phases by melting, evaporating, sublimating, freezing or condensing, but it is still water.  The "closed system" is one where the basic material is neither being created nor destroyed-- just moving between phases.

I'm not sure if what enters earth's atmosphere with meteors or is broken into atoms by the sun's power is significant enough to change what is still a "cycle" of water existing on Earth.

Answer 2

it just means that any water that is here and not taken out by humans does not go outside of the biosphere by itself.

Answer 3

water evaporates and then condenses on particles in the atmosphere.  When the particle gets heavy enough clouds form and rain happens.  Then the cycle starts again.  Has nothing to do with meteors or the sun's electrons(?)