  Using a simple two-dimensional, zero-beta model, we explore the manner by
which reconnection at a current sheet releases and dissipates free magnetic
energy. We find that only a small fraction (3%-11% depending on current sheet
size) of the energy is stored close enough to the current sheet to be
dissipated abruptly by the reconnection process. The remaining energy, stored
in the larger-scale field, is converted to kinetic energy in a fast
magnetosonic disturbance propagating away from the reconnection site, carrying
the initial current and generating reconnection-associated flows (inflow and
outflow). Some of this reflects from the lower boundary (the photosphere) and
refracts back to the X-point reconnection site. Most of this inward wave energy
is reflected back again, and continues to bounce between X-point and
photosphere until it is gradually dissipated, over many transits. This phase of
the energy dissipation process is thus global and lasts far longer than the
initial purely local phase. In the process a significant fraction of the energy
(25%-60%) remains as undissipated fast magnetosonic waves propagating away from
the reconnection site, primarily upward. This flare-generated wave is initiated
by unbalanced Lorentz forces in the reconnection-disrupted current sheet,
rather than by dissipation-generated pressure, as some previous models have
assumed. Depending on the orientation of the initial current sheet the wave
front is either a rarefaction, with backward directed flow, or a compression,
with forward directed flow.
