There is a full moon this coming Sunday. Is there a connection between the phases of the moon and the weather we Earthlings experience? Some gardeners do planting according to the moon and the full moon is associated with frost. The moon obviously affects tides – the record is at the Bay of Fundy in Nova Scotia where there is a difference in water level of 71 feet, about 22 metres. If we have clear skies, the rising full moon will look huge on the horizon. The full moon does not cause frost, although perhaps it is easier to see it by moonlight! Skies are usually clear in frost situations.
The average temperature of the Earth does rise and fall ever so slightly during a lunar month. It oscillates through a range of nearly 0.02 of a degree Celsius as the moon waxes and wanes. This variation is due to the motion of the earth and moon as they travel through space in the course of their solar orbit. We usually think of the moon revolving around the Earth. Indeed, the effect of our planet’s gravity is considerable because the moon’s mass (or weight) is only 1/80 of the Earth. However, the moon also attracts the Earth and both bodies orbit around their joint centre of mass, which is within the Earth itself. This Earth-moon combination rotates in space with the Earth slightly closer to the sun at full moon, and slightly further away when the system has swung through 180 degrees to the new-moon phase. The difference is a mere 14,400 kilometers (9,000 miles), but enough to account for the observed increase in temperature when the moon is full.