Usually one would have to mention which dispersions he is talking about, dispersion "dangling" this way it´s not common (even misleading).
"Increasing dispersion" is what we say when reffering to ratios or cause-effect, here some examples:
"Overqualification, job dissatisfaction and increasing dispersion in the returns to graduate education."
"...and which mirror the generally accepted trend of an increasing dispersion coefficient with increasing flow rate."
"Increasing consumption inequality is financed by an increasing dispersion in total income, defined as the sum of earnings and asset income."
"And Thomas (2010) document increasing dispersion for 37.9% of earnings announcements in their sample over the period 1993-2006."