Geography and Oceanography - Chapter 11 pot

Midterm #1 results posted early next week see BlackBoard Answer Keys for both White and Blue exams will be provided on course website Scantrons will be returned in labs next week Physical and Chemical Structure of the Ocean Why are the oceans blue? How is sound transmitted in the ocean? Why is the ocean “layered” in many locations? How do you keep your beer cool in the tropics? Light Absorption in Water Intensity decreases rapidly with depth Blue and green penetrate deepest, giving the ocean its color Why do objects lose their color with depth? ✦ The colors other than blue (and green) are absorbed by the water molecules in the first few meters only blue (and green) are reflected Sound in Sea Water ✦ Sound is transmitted better in water than Sound is transmitted better in water than it is in air it is in air ✦ Sound velocity in the ocean is about 1500 Sound velocity in the ocean is about 1500 m/s, or about 4 times its speed in air m/s, or about 4 times its speed in air ✦ Sound velocity increases with pressure and Sound velocity increases with pressure and temperature temperature SOFAR Sound Channel ✦ Sound is focused into the SOFAR channel because it is a low velocity region ✦ Sound is transmitted best through this channel good for whales and submarines (e.g., “Hunt for Red October”) Heard Island Experiment Global Warming faster velocity?? Go to Sounds Ocean Temperature Solar Heating ➨ Uneven heating of Earth’s surface ➨ Release of heat as infrared radiation ➨ Requires flow of heat by oceans and atmosphere ➨ Surface circulation Global Heat Budget  heat at the Earth's surface (342 W/m 2 ) is supplied by absorption of ‘short-wave’ solar radiation from the sun.  heat lost from Earth is through long-wave radiation back to space. The Greenhouse Effect ✦ The Atmosphere is transparent to sunlight (ultraviolet [UV] and visible) ✦ Clouds absorb or reflect about half ✦ Sunlight heats the Earth’s surface, which then radiates energy as longer wavelength energy (infrared) ✦ This energy is trapped by the atmospheric gases (CO 2 , H 2 O, CH 4 ) [...]...Special Properties of Water 3 RECALL: Melting and boiling points are very high Highest heat capacity of common liquids High heat of fusion and vaporization Sea Surface Temperatures only 0 -3 0°C world-wide Land: 50°C to -5 0°C Local Annual Heat Budgets  Amount of solar energy captured at one location on the Earth varies with season... Isthmus of Panama ²Net transfer of fresh water from Atlantic to Pacific Salinity of Rivers and Ocean Water Can’t just concentrate river water to get seawater How do we explain this observation? Rivers Ocean Concept of Residence Time Each element removed from ocean in different ways And at different rates e.g Cl- vs SiO2 Residence Time Flux has units of mass per unit time Reservoir has units of mass... of Sea Water (Where does Oregon’s seawater plot?) Oregon’s ocean Bottom Water Density Rules! Where does the Ocean’s Deepest Water Come From? 3 The densest seawater is COLD and SALTY 3 This is formed at high latitudes in the North and South Atlantic: North Atlantic Deep Water (NADW) Antarctic Bottom Water (AABW) 3 Could dense seawater form in the tropics? (evaporation!) Dissolved Gases in the Ocean Important... Temperature (vertical profile) Seasonal changes in temperature profile Temperature (vertical profile) Thermocline Cool drinks go here Temperatures with Depth 3 Thermocline sharp temperature change Evaporation - Precipitation 3 Over the oceans, evaporation exceeds precipitation 3 The balance is restored by rain over the continents, returning water via rivers Evaporation vs Precipitation Climate Belts Ocean Surface... the Ocean Important Gases in the Ocean 3 Oxygen Respiration, Decomposition 3 CO2 Photosynthesis, CaCO3 3 Nitrogen Nutrient for growth (NO 3) 3 Methane a product of decomposition Photosynthesis and Respiration 3 Biology interacts with the Chemistry Dissolved Oxygen Biochemical Recycling . Water ✦ RECALL: Melting and boiling points are very high Highest heat capacity of common liquids High heat of fusion and vaporization Sea Surface Temperatures only 0 -3 0°C world-wide Land: 50°C to -5 0°C Local. decreases rapidly with depth Blue and green penetrate deepest, giving the ocean its color Why do objects lose their color with depth? ✦ The colors other than blue (and green) are absorbed by the. or about 4 times its speed in air ✦ Sound velocity increases with pressure and Sound velocity increases with pressure and temperature temperature SOFAR Sound Channel ✦ Sound is focused into the