Pressure factor as a function of perihelion distance. Mete-oroid masses and spectra are marked as in Fig. 4. Vertical dashed lines indicate the semimajor axes of Venus, Mercury, and the distance of 0.07 AU. Regions where members of the Southern δ Aquariids, Geminids, December Monocerotids, Taurids and Perseids meteor showers are found are highlighted. Actual meteoroids belonging to the first four showers are marked by white dots.