Showing papers on "Convective available potential energy published in 1975"

The effects of vertical wind shear on the evolution of convective clouds

Abstract: The effects of ambient wind shear Uo on the evolution of an isolated three-dimensional convective cloud are studied. Sixteen cases are considered which differ from one another both in the value of U′0 in the initial value of the energy of atmospheric instability per unit height of the unstable layer, E0. It is found that convective clouds may be grouped into two types, ‘weak’ and ‘strong’: if E0/H < 0−65 × 102cm s−2 then convection is ‘weak’; if E0 0−65 × 10−2cm s−2 then convection is ‘strong’. For ‘weak’ convective clouds there is a critical value of shear, U′0cr |U′0| < U′0crthere is an inhibiting effect on the development of convection; and for |U′0| U′0 its evolution is completely suppressed. The essential new result is that ‘strong’ convective clouds are intensified under the effect of U′0. In this case there is a resonance value of shear, U′0res at which the degree of the intensification of convection has a maximum (30–40%).