Global models of the atmosphere are traditionally used in weather forecasting and climate research.
Global weather forecast models predict the temporal development of the state of the atmosphere within a period of one or two weeks on the basis of a possibly accurate analysis of the initial condition. The spatial resolution can be as high as the available computer capacity permits.
Climate research model simulations have to cover much longer periods of several decades. This can only be realized on the cost of the spatial resolution. The initial condition is less important than an appropriate consideration of essential parts of the climate system, e.g. the oceans, the cryosphere and the biosphere. In addition, short living chemical trace substances (e.g. ozone, aerosols) are incorporated as interactive components of the climate models as they act on the radiation budget of the climate system while their distribution is modified by the state of the atmosphere.