Lecture 4 Tides

Tides

Three Players – Earth, Moon, Sun

-moon is the most important element

GRAVITATION

G M

1/R2

Gravitational force =

M MR

Gravitational bulge

Gravitational bulgeCentrifugal bulge

C • • •B A

• • •

Gravitational force

Earth Moon

A little more reality

Path of moon’s centre

Path of earth’s centre

Both the earth and the moon revolve around their common centre of gravity

•Common centre of gravity

A little more reality

x

Common centre of gravity

Path of earth’s centre

1

2

3

4

A little more reality

A little more reality

Daily advance of peak tide

Daily advance of peak tide

Daily change of tide heights

Daily change of tide heights

Different tide cycles

Different tide cycles

Different tide cycles

Diurnal Tide

Different tide cycles

Semidiurnal Tide

Different tide cycles

Mixed Semidiurnal Tide

Different tide cycles

Coriolus forces

Coriolus forces

Coriolus forces and gyres

Coriolus forces and gyres

Amphidromic points

Amphidromic points - Animation

Amphidromic Points - Gulf of St. Lawrence

Tide Levels and Chart Datum

Mhws - Mean High Water on the Spring tide

Mhws - Mean High Water on the Neap tide

Mhws - Mean Low Water on the Spring tide

Mhws - Mean Low Water on the Neap tide

MHWS

MLWS

MHWN

MLWN

MTL Spring Range

NeapRange

Mtl - Mean Tide Level

Chart Datum

Tidal Bore

Bay of Fundy Tides

Bay of Fundy Tides

Bay of Fundy Tides

Determination of Tide Level

Finding the tide

Primary port

Secondary ports

Tides and Weather

Tides and Weather

Tides and Weather

Tides and Weather

Tides and Weather

Parlee Beach

Tides and Weather

Saxby Gale - 1869

Hurricane Sandy

Hurricane Sandy

Hurricane Sandy

Hurricane Sandy

Next time

Waves and Currents