What is the difference between lunar and solar tides

Once a month, when the moon is closest to the Earth at perigee , tide-generating forces are higher than usual, producing above-average ranges in the tides. About two weeks later, when the moon is farthest from the Earth at apogee , the lunar tide-raising force is smaller, and the tidal ranges are less than average.

A similar situation occurs between the Earth and the sun. When the Earth is closest to the sun perihelion , which occurs about January 2 of each calendar year, the tidal ranges are enhanced. When the Earth is furthest from the sun aphelion , around July 2, the tidal ranges are reduced Sumich, J. Once a month, at perigee, when the moon is closest to the Earth, tide-generating forces are higher than usual, producing above average ranges in the tides. If there were no Moon, the daily tidal period would be exactly 24 hours.

The orientation of the Moon and the Sun vary in relation to each other over the lunar cycle. The different phases of the Moon are a manifestation of this variation. This change in orientation also causes tidal heights to vary predictably over the monthly cycle. The illustration above explores how the Earth-Moon-Sun orbital system causes daily and monthly tidal patterns.

The illustration uses a simplified system that assumes tides occur on a perfectly spherical, water-covered Earth that rotates around its own center of gravity. Additional factors influence real tidal patterns, but given the overwhelming influence of the Moon, a simplified model that includes only the Moon provides substantial explanatory power for daily tidal patterns.

The addition of the Sun and the interactions between the Sun and the Moon explain monthly tidal patterns. Follow SciencePrimer. Skip to main content.

There is a high or low tide once every 6 hours and 12 minutes. High tides occur about 12 hours and 25 minutes after the previous high tide. Same for low tides, they occur about once every 12 hours and 25 minutes.

Every day, high and low tides occur about 50 minutes later than they did on the previous day. These occur during full and new Moons when the gravitational influence of the Sun and the Moon line up with each other.

Viewing the page as a clock, if the sun is at 9 o'clock, the moon will be at 6 o'clock. This is the first-quarter position. With the high tides produced by the sun and the moon at degree angles, the solar high tide partly fills in the lunar low tide.

These tides, which have the lowest change in height between high and low tides, are called neap tides. Notice the addition of the tides when the moon is full. You total tide cycle should look like this:.

The force of the sun on you as you stand on the surface of the earth is times greater than the force of the moon on you.