# 6.1: Lesson 6 Introduction

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Source: Grand Départ Tour de France 2016(link is external)

In this lesson, we will focus on the origin of ocean tides. We'll look at things in terms of an equilibrium (simple) model and in terms of a dynamic model of tides that takes into account factors such as ocean basin geometry and coastlines.

By the end of this lesson you should be able to explain the role of gravity, inertia, and rotating reference frames in determining tides. You should be able to describe why, in the equilibrium theory of tides, there are two tidal bulges on Earth; one that is roughly under the moon and one that is roughly antipodal to that.

The concept of Amphidromic points is important in understanding tidal circulation in the oceans. You should be able to describe how amphidromic circulation works, including co-tidal lines, co-range lines, and the role of the Coriolis effect.

## What will we learn in Lesson 6?

By the end of Lesson 6, you should be able to:

• Describe how the Earth-moon system rotates during a lunar month, and why the focal point is within but not at the center of Earth.
• Explain the role of gravity, inertia, and rotating reference frames in determining tides.
• Describe why semi-diurnal tides involve two high tides and two low tides at a given location during roughly a 24 hr. and 50 min period.
• Describe why the concept of Amphidromic points is important in understanding tidal circulation in the oceans.
• Describe how amphidromic circulation works, including co-tidal lines, co-range lines, and the role of the Coriolis effect..
• Use on-line resources to construct maps of ocean temperature and salinity

## What is due for Lesson 6?

The chart below provides an overview of the requirements for Lesson 6. For assignment details, refer to the lesson page noted. See the Course Schedule (located in the Resources menu) for assignment due dates.

Lesson 6 Assignments