Tides

Tides

Multiple Choice

Before we begin, what do you THINK causes ocean tides?

• wind

• underwater earthquakes

• The Earth's rotation

• The gravitational pull between the Earth,sun and the moon

What causes tides?

Tides are caused by the gravity of both the moon and the sun “pulling” at the water in the sea. Because the Earth is constantly turning, the “pull” of gravity affects different places as each day goes on – so when the tide is “out” in your area, it is “in” somewhere else

How many tides?!

The overall effect of these tidal forces is to “squeeze” the oceans, and produce two tidal bulges on opposite sides of the Earth—one facing the Moon and a slightly smaller one facing away from the Moon. Because the Earth rotates, each place on our planet experiences TWO high tides and TWO low tides each day.

Multiple Choice

What is a high tide?

• Sea pulled TOWARD the moon where Earth is CLOSEST to the moon

• Sea pulled AWAY from the moon where Earth is FARTHEST to the moon

• Sea pulled AWAY from the moon where Earth is CLOSEST to the moon

Multiple Choice

If tides alternate from high to low and there are two of each type of tide a day, about how many hours will generally be between each different tide?

• 2 hours

• 6 hours

• 12 hours

• 24 hours

What about the Sun?

The Sun affects the ocean tides, but the Moon plays the biggest role. Although the Sun's gravitational pull on the Earth is 178 times stronger than the Moon's, the Moon is much closer to our planet, so it has more impact on tides than the Sun. The Sun's gravitational force, DOES affect the tides, though. Just not as much as the Moon.

SPRING tides

Spring tides are a special event that happens when the Moon and Sun are BOTH lined up. This makes the gravitational pull VERY strong and the high tides are EXTREMELY high. This happens every two weeks when the moon is in the full moon phase, or new moon phase.

NEAP tides

Seven days after a spring tide, the sun and moon are at right angles to each other. When this happens, the bulge of the ocean caused by the sun partially cancels out the bulge of the ocean caused by the moon. This produces moderate tides known as neap tides, meaning that high tides are a little lower and low tides are a little higher than average. Neap tides occur during the first and third quarter moon, when the moon appears "half full."

Multiple Choice

Tides are caused mainly by what?

• Moon’s gravitational pull
• Sun’s gravitational pull
• Earth’s gravitational pull

Multiple Choice

Why does the moon's gravitational pull have more of effect on tides than the sun's gravitational pull?

• they are the same
• the moon is larger than the sun
• tides are not caused by the moon
• the moon is closer to the Earth than the sun

Multiple Choice

What type of tides would this arrangement of earth-moon-sun create?

• neap tide
• spring tide
• new moon tide
• full moon tide

Multiple Choice

What type of tide would this arrangement of earth-moon-sun create?

• full moon tide
• new moon tide
• neap tide
• spring tide

Multiple Choice

What is a difference between spring and neap tides?

• Spring tides occur when the earth and sun are IN LINE with the new or full moon.

• Spring tides occur when moon in 3rd or 1st quarter phases

• Spring tides are LOWER than neap tides

• Spring tides occur in Spring and neap tides can occur in any season

Multiple Choice

What is a difference between spring and neap tides?

• Spring tides occur when the earth and sun are IN LINE with the new or full moon.

• Spring tides occur when moon in 3rd or 1st quarter phases

• Spring tides are LOWER than neap tides

• Spring tides occur in Spring and neap tides can occur in any season