Basically rain water is formed in clouds after it's been sucked up into the air into the clouds through evaporation.
When water lands on the ground or is already on the ground the hot sun eventually evaporates the water and leads to condensation.
When that water gets sucked up into the sky it then eventually returns to the ground through rain clouds after the clouds release the rain in the form of rain, snow, sleet etc.
Snow, sleet and hail are essentially just frozen rain that got too cold before it reached the ground and formed into the snow, hail and sleet.
Water is in a constant cycle of being brought to the ground and evaporated back up into the air into the clouds which it then returns.