We are experiencing a fairly unusual astronomic event right now, the spring perigean tide.

The term “spring tide” refers to the higher high tides and lower low tides which occur at the new and full moons. During the full and new moons, the Earth, sun, and the moon are aligned in a way that we see a higher tidal departure.  Spring tides alternate at one week intervals with “neap tides.“ Neap tides occur during the first or third quarter moons when the sun and moon are aligned at right angles with respect to earth, and the sun tides subtract from the moon tides.

A perigean tide occurs when the moon is closest to the earth. The moon’s orbit around the earth is elliptical, so the distance between earth and moon is in constant flux. The perigee refers to the time when the moon and the earth are closest to one another.  Perigee is reached about once a month.  Remember, the moon’s impact on tides is greater as it moves closer to the Earth.

The largest astronomical tides, perigean spring tides, which is what we are experiencing now, occur when spring tides and perigean tides coincide. These usually occur about every six months.