A code involving two spatial dimensions and three velocity dimensions is used to model the tail of earth's magnetosphere in a continuation of earlier work using a one-dimensional code. The model assumes the existence of an externally imposed convection electric field and the presence of cold particles in the lobes of the magnetotail. The model reproduces the results of the previous one-dimensional model. In addition, the two-dimensional model exhibits the development of turbulence which persists so long as cold lobe particles are being convected into the neutral sheet. The model also exhibits the earthward jetting of plasma, which becomes particularly intense after the tail field begins to collapse toward a more dipolar configuration. Magnetic energy is converted into energy of bulk motion. The model is used to identify the physical processes that may occur during the growth and recovery phases of substorms. It is also shown that if the convection electric field is strong enough, the magnetic energy of the tail will increase, resulting in a more extended magnetotail.