Bài giảng Hải dương học: Chương 4

Bài giảng Hải dương học: Chương 4 - Thủy triều có nội dung trình bày thuật ngữ thiên văn và thủy văn, lực tạo triều, phân tích thủy triều, dự báo triều, thủy triều biển đông, cửa sông và thủy triều vùng cửa sông.
Nội dung trích xuất từ tài liệu:
Bài giảng Hải dương học: Chương 4 Chapter 4 Tide and tidal currents Nội dung1. ThuËt ng÷ thiªn v¨n vµ thuû v¨n ng÷2. Lùc t¹o triÒu3. Ph©n tÝch thuû triÒu4. Dù b¸o triÒu5. Thuû triÒu BiÓn ®«ng ®«ng6. Cöa s«ng vµ thuû triÒu vïng cöa s«ng7. Bµi tËp ThuËt ng÷ thiªn v¨n ng÷ Thiªn cÇu hay mÆt cÇu bÇu trêi Trôc vò trô Thiªn cùc b¾c vµ thiªn cùc nam Thiªn ®Ønh vµ thiªn ®Õ MÆt ph¼ng ch©n trêi §-êng ch©n trêi, xích đạo trời. trêi, trời. Thiªn cÇu b¾c vµ thiªn cÇu nam. nam. Kinh tuyÕn trêi. trêi. §iÓm b¾c vµ ®iÓm nam, ®iÓm ®«ng vµ ®iÓm t©y. nam, ®«ng t©y. Vßng giê, vßng nhËt ®éng. Vßng hoµng ®¹o, b¹ch ®¹o. giê, éng. ®¹o. Xu©n ph©n (21/III),thu ph©n (23/IX),h¹ chÝ (22/VI), ®«ng chÝ (22/XII). (21/III),thu (23/IX),h¹ ®«ng Ngµy sãc th-îng huyÒn , ngµy väng h¹ huyÒn . ThuËt ng÷ thuû v¨n ng÷ - §Ønh triÒu - Ch©n triÒu - Tr, Td - Kú n-íc c-êng, kú n-íc kÐm - Chu kú triÒu - “0 lôc ®Þa” , “0 ®é s©u” - §é lín thuû triÒu - Biªn ®é triÒu Tidal Characteristicssinglewaves - stretch across entire ocean basins.shallow -water waves shallow- – wavelengths greatly exceed the depth of the ocean.complex interactions of moon and sunWhy Care About Tides?AquacultureThe Tides of the Bay of Fundy Origin of the TidesUnlike wind- wind-driven surface waves and unlike tsunamis, tides are caused by two principal factors: – Gravitational attraction – Centrifugal force Gravitational AttractionAll masses are drawn to each other.The moon because of its closeness to the Earth exerts a greater gravitational effect on the Earth than the Sun, despite the fact that the Sun Sun, is much more massive than the Moon. x=? Gravitational Effect of MoonCentrifugal Forces: Center of Rotation2 Bulges from Gravitational Attraction & Centrifugal Force Gravitational forces Tractive force 3gMFs  Fm  sin(   )  Fa  sin( ) Fs   sin 2 2K 3 Distribution of tractive forces over the Earth surface.Ratio of the tractive forces od the Moon and the Sun. Symbol Moon Sun Dimension M 0.0123 333,000 (-) K 60.3 23,500 (-) 3gM/(2K3) 0.82*10-6 0.38*10-6 (m/s2) The equilibrium theoryassumed that the Earth is fully covered with water The plane of the moon is in the plane of the equator why not exactly 24 hours or 12 hours? Moon moves forward in it’s orbit each day. – Takes 50 additional minutes for a spot on the Earth’s surface to regain it’s position relative to the Moon. E = 15.041 o/h m = 0.549 o/h 2 360o 2T    24.84h E  m  14.49 /h o T = 12.42 h = 12 h 25’ Theplane of the moon makesan anglewith theplane of theequatorJoint effect of moon and sun on the tides  Spring tides occur when the Earth, Sun, and Moon are aligned. – New Moon and Full Moon phases – Constructive interference  Neap tides occur when the Sun and Moon are aligned at right angles to one another. – Quarter Moon phases – Destructive interference Spring tide: tide: phase when tidal range is maximal. maximal. Neap tide: phase when tidal range is minimal. tide: minimal. There are 2 spring and 2 neap tides each month 2 360o 2T   708h m  s  o 0.508 /h T = 354 h = 14.8 daysMoving position of the perigeumElliptical orbit of the EarthRelative motions of moon and sun in relation to the celestrial sphere 3gM 3gM  n  ...