Tides. Definition : the periodic rise and fall of sea level within a day a. tides are measured relative to points on land b. highest level = high tide c. lowest level = low tide Tidal Ranges : the difference in feet, or meters, between a high tide and the next low tide
a. tides are measured relative to points on land
b. highest level = high tide
c. lowest level = low tide
a. Gravitational forces causes the Earth and moon to be pulled towards one another
b. The liquid on the side of the Earth closest to the moon is pulled toward the moon, producing a bulge.
c. The center of the Earth is also pulled toward the moon. Thus, the water on the opposite side of the earth is ‘left behind’ causing a bulge on the opposite side of the Earth.
d. Because there are two bulges, a point on Earth experiences two high tides and two low tides in one day!
a. The moon rotates around the earth at a rate of 12/day (1 revolution/month)
b. The rotation is in the same direction as the earth’s spin
c. By the time the earth has completed one rotation, the moon has shifted 12 ! So, it takes an extra 50 minutes for the moon to be in the same position relative to a point on earth.
d. A tidal cycle is24 hours and 50 minutes!
High and Low tides are 50 minutes later every day!
a. Because of it’s size, the sun exerts a gravitational force 180 times stronger than the moon!
b. BUT, gravitational attraction decreases as the distance between bodies increases
c. The sun’s influence on tides is much smaller than the influence of the moon
d. The sun’s pull can either heighten the moon’s effects or counteract them depending on where the moon is in relation to the sun