Heating rate E _H ( t) is given by a Gaussian function (thin solid curve). The density function n( t) follows the time integral (thick solid curve) of this Gaussian function (for a constant value of dn _evap/ dE _H ) according to the Neupert effect, which can be approximated by a semi-Gaussian function (dashed curve). The time t _m of the maximum heating rate and the time t _p of the peak density are indicated with dotted lines.