How do you measure light intensity, oxygen concentration and relative humidity?

Question

All of which are Abiotic factors

Answer 1

Electronic light meters are available from companies that sell scientific instruments.  These can be calibrated to read out in units of quantum flux, watts, lumens, etc.  It depend on what you want to use it for.

Oxygen concentration again requires an electronic device that uses an electrode to respond to the O2 level in the medium.  But, O2 levels in air are very stable and therefore not worth monitoring.  But, in aqueous environments the O2 level can vary widely as a result of photosynthesis or respiratory activity by biota.

Relative humidity is most easily measured using a wet bulb/dry bulb thermometer system which is again available from a scientific supply retailer.  Use of such a system is usually included with the purchase or can be obtained from various literature sources.