The diurnal variations of electron content NT and shape factor F observed at an equatorial station during sunspot minimum are shown to be consistent with the electron density profiles Ne(h), observed at Jicamarca during sunspot minimum. The rapid increase in NT and F at sunrise results from the EUV production of ionization in the E and F regions. Day-to-day variations in daytime NT are observed to be quite small at the equator. The evening decrease in F results from an upward drift of the F region at sunset and the evening decay of the E and bottomside F regions. The nighttime peak or plateau in F is produced by the slow downward drift of the electron density profile. The deep predawn dip in F is caused by the main peak of the F layer reaching low altitudes where high loss rates cause a large reduction in ionization below 300 km and a very flat Ne(h) profile.