The Supermoon's Super Tide

December 07, 2016



Photographer: Patti Weeks
Summary AuthorPatti Weeks

With so much focus on the dramatic November 14, 2016, supermoon, many of us took the advantage to gaze upward at our only natural satellite. But for those people living near the sea there was also an opportunity to look down to examine its effect on the tides. Both the high and the low tides are at their most extreme during supermoons.

Tides are caused by the gravitational forces of the Moon and the Sun on the Earth, and the rotation of the Earth. The Moon orbits the Earth approximately every 28 days in an elliptical path. At perigee, when the Moon is closest to the Earth, its gravitational pull on the tides is at its strongest. When furthest from the Earth, apogee, the Moon's gravitational pull is weaker.

Spring tides occur twice each month when the full or new Moon is in near-alignment with the Earth and the Sun. This Sun-Earth-Moon alignment is referred to as syzygy. The compound gravitational pull of the Moon and Sun during syzygy causes the oceans to bulge a bit more than usual. Perigean spring tides occur about three or four times a year when syzygy is occurring and the Moon is at perigee, causing the tidal range to be even greater.

The November 2016 supermoon created slightly higher than normal perigean spring tides at my location in coastal North Carolina. Fortunately, weather conditions were not conducive to cause coastal flooding here. The top photograph was taken from Atlantic Beach, North Carolina, during the morning high tide of November 14, 2016. This picture captures a lingering mist, rougher-than-usual incoming waves and the intermittent morning sunlight reflecting off the buildings on the Emerald Isle, North Carolina shoreline, 17 mi (27 km) westward. The second, east-facing, photo shows rough waves at high tide near a pier at the Atlantic Beach oceanfront.

Photo Details: Top - Camera Maker: SONY; Camera Model: DSC-HX400V; Lens: Sony 24-210mm F2.8-6.3; Focal Length: 210.47mm; Aperture: ƒ/6.3; Exposure Time: 0.0040 s (1/250); ISO equiv: 100; Bottom: Camera Maker: SONY; Camera Model: DSC-RX100M4; Lens: Sony 24-70mm F1.8-2.8; Focal Length: 25.7mm (35mm equivalent: 70mm); Digital Zoom: 1.938x; Aperture: ƒ/4.0; Exposure Time: 0.0025 s (1/400); ISO equiv: 125.