In human resources the irritation threshold is the

The right answer is a point at which a person notices something and becomes annoyed.  

In science, a threshold effect refers to the appearance of a phenomenon from a certain value of a variable.

In psychology, irritability is a trait of a character indicating a propensity for angry reactions.

So the threshold of irritability designates the appearance of an angry reaction from a determined intensity of stimulation (below this value, there is no reaction).

he movement of air through earth's or any planet's atmosphere is called wind, and the main cause of earth's winds is uneven heating by the sun. this uneven heating causes changes of atmospheric pressure, and winds blow from regions with high pressure to those with low pressure.

i hope this : )