Complex sentence: Space weather models differ from meteorological model in that amount of input is vastly smaller and no single space weather model yet can reliably predict the environment from the surface of the Sun to the bottom of the Earth's ionosphere.
Split into simpler sentences: Space weather models differ from meteorological models in that the amount of input is vastly smaller. No model can yet reliably predict the environment from the surface of the Sun to the bottom of the Earth's ionosphere.