  We studied the macro evolution of the micro atmospheric glow discharge
generated between a micro argon jet into ambient air and static water. The
micro discharge behaves similarly to a complex ecosystem. Non-linear behaviors
are found for the micro discharge when the water acts as a cathode, different
from the discharge when water behaves as an anode. Groups of snapshots of the
micro discharge formed at different discharge currents are captured by an
intensified charge-coupled device with controlled exposure time, and each group
consisted of 256 images taken in succession. Edge detection methods are used to
identify the water surface and then the total brightness is defined by adding
up the signal counts over the area of the micro discharge. Motions of the water
surface at different discharge currents show that the water surface lowers
increasingly rapidly when the water acts as a cathode. In contrast, the water
surface lowers at a constant speed when the water behaves as an anode. The
light curves are similar to logistic growth curves, suggesting that a
self-inhibition process occurs in the micro discharge. Meanwhile, the total
brightness increases linearly during the same time when the water acts as an
anode. Discharge-water interactions cause the micro discharge to evolve. The
charged particle bomb process is probably responsible for the different
behavior of the micro discharges when the water acts as cathode and anode.
