(LFC) the level at which a parcel of saturated air becomes warmer than the surrounding air and begins to rise freely. This occurs most readily in a conditionally unstable atmosphere.
See Level of Free Convection
Air parcels rising up from the ground or some other surface
Or Lifting Condensation Level (LCL). The level at which a parcel of moist air becomes saturated when it is lifted dry adiabatically.
(LI) A common measure of atmospheric instability. Its value is obtained by computing the temperature that air near the ground would have if it were lifted to some higher level (around 18,000 feet, usually) and comparing that temperature to the actual temperature at that level. Negative values indicate instability - the more negative, the more [...]
A region of relatively strong winds in the lower part of the atmosphere. Specifically, it often refers to a southerly wind maximum in the boundary layer, common over the Plains states at night during spring and summer.