On other days I found condensation levels were low or non-existent.

Such cooling may occur as air pressure reduces with altitude, as noted in the article on lifted condensation level.

Usually the level at which water vapor changes into liquid marks the base of the cloud in the atmosphere hence called condensation level.

Condensation:low or non-existent condensation levels in warm weather.

The altitude at which this begins to happen is called the lifted condensation level, which roughly determines the height of the cloud base.

Espy's formula for Lifted condensation level (cloud base)

With the help of these lines, parameters such as cloud condensation level, level of free convection, onset of cloud formation.

Lifting condensation level (LCL) (Glossary of Meteorology)

The convective condensation level (CCL) represents the height where an air parcel becomes saturated when lifted adiabatically to achieve buoyant ascent.

An absence of sufficient condensation particles at and above the condensation level causes the rising air to become supersaturated and the formation of cloud tends to be inhibited.

Cloud droplets form when the air is lifted beyond the condensation level where water vapor condenses on so-called nuclei; (small particles) that grow to a size of typically 0.02 mm (.001 in).

As a parcel of air lifted in a thermal rises, it also cools, and water vapour will eventually condense to form a cloud if the parcel rises above the lifted condensation level.

In such case, cloud base begins at the convective condensation level (CCL), whilst with mechanical lifting, condensation begins at the lifted condensation level (LCL).

The convective condensation level (CCL) results when strong surface heating causes buoyant lifting of surface air and subsequent mixing of the planetary boundary layer, so that the layer near the surface ends up with a dry adiabatic lapse rate.

The usual way of finding the LFC is to lift a parcel from a lower level along the dry adiabatic lapse rate until it crosses the mixing ratio line of the parcel: this is the lifted condensation level (LCL).

The air here should be about 60 to 65% RH, which is then lifted along the dry adiabat (see also adiabatic process) to the lifting condensation level (LCL), which is the intersection of that curve with the average mixing ratio in the boundary layer.

The lifted condensation level or lifting condensation level (LCL) is formally defined as the height at which the relative humidity (RH) of an air parcel will reach 100% when it is cooled by dry adiabatic lifting.

This altitude is known as the lifting condensation level (LCL) when mechanical lift is present and the convective condensation level (CCL) when mechanical lift is absent, in which case, the parcel must be heated from below to its convective temperature.

If the environmental lapse rate is larger than the dry adiabatic lapse rate, it has a superadiabatic lapse rate, the air is absolutely unstable - a parcel of air will gain buoyancy as it rises both below and above the lifting condensation level or convective condensation level.