# If a parcel of air is heated, what will happen to its density?

$P V = m R T$
$\frac{m}{V} = \setminus \frac{P}{R T}$
$\setminus \rho = \setminus \frac{P}{R T}$
Thus, assuming the pressure of parcel of air is constant during heating then $\setminus \rho \setminus \propto \setminus \frac{1}{T}$ i.e. when temperature $T$ of parcel of air is increased the its density will decrease.