When monitoring bearings should you have a minimum load on the equipment?
I also came across an article that said humidity and temperature can effect the results.
any comments?

I think its important to have a consistent load on the bearing each time you collect data. That is to say that data taken in January and then taken again in February should be taken under the same circumstances (load and rpm) Taking ultrasound readings in the same position is equally important. For instance in the load zone (6 o'clock for instance) each time or at 12 o'clock each time. The trick is to aim for consistency and control as many variables as possible.