2 (i.c.b.) Daily versus monthly Tide Cycle
Tides happen regularly no matter how the wind blows.
The Daily Tide Cycle:
As Earth turns completely around once each day, people on or near the shore observe the rise of tides as they reach the area of a tidal bulge. High tides occur about 12 hours and 25 minutes apart in any location.
The Monthly Tide Cycle
The sun pulls the water on Earth’s surface toward it. Changes in the positions of Earth, the moon, and the sun affect the heights of the tides during a month.
Twice a month, at the new moon and the full moon, the sun and moon are lined up. Their combined gravitational pull produces the greatest difference between the heights of high and low tide, called a spring tide. These tides get their name from an Old English word, springen, which means “to jump.”
At the first and third quarters of the moon, the sun and moon pull at right angles to each other. This arrangement produces a neap tide, a tide with the least difference between low and high tide. During a neap tide, the sun’s gravity pulls some of the water away from the tidal bulge facing the moon. This acts to “even out” the water level over Earth’s surface, decreasing the difference between high and low tides.
Spring tides and neap tides are caused by the positions of Earth, the sun, and the moon. When the moon, sun, and Earth are in a straight line, a spring tide occurs. When the moon is at a right angle to the sun, a neap tide occurs.
The Daily Tide Cycle:
As Earth turns completely around once each day, people on or near the shore observe the rise of tides as they reach the area of a tidal bulge. High tides occur about 12 hours and 25 minutes apart in any location.
The Monthly Tide Cycle
The sun pulls the water on Earth’s surface toward it. Changes in the positions of Earth, the moon, and the sun affect the heights of the tides during a month.
Twice a month, at the new moon and the full moon, the sun and moon are lined up. Their combined gravitational pull produces the greatest difference between the heights of high and low tide, called a spring tide. These tides get their name from an Old English word, springen, which means “to jump.”
At the first and third quarters of the moon, the sun and moon pull at right angles to each other. This arrangement produces a neap tide, a tide with the least difference between low and high tide. During a neap tide, the sun’s gravity pulls some of the water away from the tidal bulge facing the moon. This acts to “even out” the water level over Earth’s surface, decreasing the difference between high and low tides.
Spring tides and neap tides are caused by the positions of Earth, the sun, and the moon. When the moon, sun, and Earth are in a straight line, a spring tide occurs. When the moon is at a right angle to the sun, a neap tide occurs.
