Low relative humidity during the
night, i.e. the absence of dew, caused pollen emission
immediately at sunrise consistent with previous measurements
performed by Jarosz et al. (2005). On four consecutive
days, daily pollen concentration patterns were bi-modal
during the morning hours while on other days only a single
peak distribution was observed. Diurnal, bi-modal corn pollen
distributions were previously reported by Flottum et al. (1984)
without providing an explanation for them.