  The day-night variation of cosmic rays intensity at sea level has been
observed by a simple G-M counter telescope. We preform two 5 hours counting
during the day and night and find that the pattern of variation is closely
related to the atmospheric disturbance, especially when the observation station
is being affected by meterological front or trough. Such effects may lasts for
a few days until the trough or fronts weakened. The pattern of variation may be
negatively correlated to the altitude of the 0 degC level of the atmosphere.
This is closely related to the muon decay effect in the atmosphere. The
phenomenon should be further investigation for possible application in weather
forecasting.
