At any given time, there are two high tides on the earth, the direct tide on the side facing the moon and the indirect tide on the opposite side. As the earth rotates on its axis, the location of the two diametrically opposed tidal bulges varies on the earth's surface. The earth's rotation and the moon's revolution, which have the same direction, bring each point on the earth opposite the moon once every 24 hr and 50 min. Therefore, the average interval between direct and indirect high tides is about 12 hr and 25 min. In many places along the Atlantic coasts of N America and Europe, the two daily low tides are of nearly equal duration and magnitude, called semidiurnal tides.
In certain shallow seas and narrow estuaries, the tides differ from this simple pattern. For example, in certain regions such as the Pacific coast of N America, one of the two daily tides is appreciably higher than the other or the interval between successive tides is unequal; these are called mixed tides. In other regions, such as the Gulf of Mexico, there is only one high tide per day called a diurnal tide, with a period of 24 hr and 50
>>>At any given time, there are two high tides on the earth, the direct tide on the side facing the moon and the indirect tide on the opposite side. As the earth rotates on its axis, the location of the two diametrically opposed tidal bulges varies on the earth's surface. <<<<<
Pah!. This is obviously rubbish. We have two tides per day because the Earth is flat. All the water swills to one side when the moon comes up, and then swills back of its own accord when the moon goes down. Try it with a horizontal half-full pop bottle.
These 'round Earth' theories are pure claptrap. Just look at any Chart. All of them are FLAT!
Ah Nick..why then are there no tides in the Med. Should the water not be able to rush past the Straights of Gibralter just like the space we sail through to come into the Marina.The straights are much wider too so it should be easier to rush past
Nick, a fantastic explanation, but sorry I've tried to simulate both yours and Sue's explanation in the kitchen laboratory and Sue definately has it right. DaveJ
Its obvious! In cosmic terms, the Mediterranean is a puddle - effectively an inland lake and is therefore less affected. It does have tides anyway even if they are 2" at neaps and 4" at springs.