Circulation of the Air and Oceans

I. Air Circulation A.Uneven heating of earth’s surface B. Seasonal changes in temperature & precipitation C. Rotation of the earth on its axis Coriolis Effect—because the earth is rotating anything that moves over its surface tends to turn to one side rather than moving in a straight line. Coriolis Effect—because the earth is rotating anything that moves over its surface tends to turn to one side rather than moving in a straight line. deflection of winds to right in N and left in Sdeflection of winds to right in N and left in S

II. Chemical Make-up of Atmosphere A. Greenhouse Gases Traps energy from escaping atmosphere warming air Traps energy from escaping atmosphere warming air B. Greenhouse Effect Natural warming of atmosphere Natural warming of atmosphere Necessary for Earth Necessary for Earth

C. Global Warming  Unnatural warming of the Earth  Caused by human activity; ie burning of fossil fuels  Increase greenhouse gases in atmosphere to unnatural levels  Heavily debated as to rate of occurence

D. Ozone Layer  Oxygen(O 2 ) conversion to Ozone (O 3 )  Prevents 95% of UV radiation from reaching earth’s surface

E. Depletion of Ozone Layer  CFCs in atmosphere due to human activity  C,F, Cl break apart bonds between oxygen molecules  Result in new compounds; less ozone  UV radiation allowed to reach earth’s surface  DNA mutations

III. Ocean Currents A. Large scale currents 1. Gyre – large circular systems of surface currents; redistribution of heat & moisture; warm the western sides of oceans; ex. Gulf Stream along eastern US coast 1. Gyre – large circular systems of surface currents; redistribution of heat & moisture; warm the western sides of oceans; ex. Gulf Stream along eastern US coast 2. Upwelling —cold, nutrient rich bottom water move to the surface along steep coastlines

Ocean Currents, cont. 3. Thermohaline – changes in density from temperature & salinity changes; vertical movement; downwelling = sinking of more dense water; upwelling = rising of less dense water a. North Atlantic Deep Water b. Antarctic Bottom Water – denser, moves under NADW, causes upwellings 4. Thermocline – changes in temperature cause circular currents in the water column

Ocean Currents, cont. B. Smaller scale currents 1. Longshore current – travels north to south, causes sand to move from north end of islands to south end - “River of Sand” (barrier islands erode on N and grow on S), caused by swash and backwash, creates a spit on the island (hook shape on S end); people attempt to stop the erosion by building jetties/seawalls, moving the sand, etc

Ocean currents, cont. 2. Waves  caused by wind energy  wind transfers some of its energy to the water through friction between the air molecules and the water molecules  size depends on velocity of wind, length of time wind blows, fetch (distance the wind blows)  water molecules move in circular pattern  energy transferred from molecule to molecule as wave moves; upon breaking, energy is transferred to the beach (erosion and sediment deposition)

Tides Tides are periodic rises and falls of large bodies of water

Causes for Tides  Tides are caused by the gravitational interaction between the Earth, the Moon, and the sun. The gravitational attraction of the moon causes the oceans to move out in the direction of the moon The gravitational attraction of the moon causes the oceans to move out in the direction of the moon On the opposite side of the earth the ocean moves out as well due to the fact that the moon’s gravitational pull is at its weakest and the earth itself is also being pulled in the direction of the moon On the opposite side of the earth the ocean moves out as well due to the fact that the moon’s gravitational pull is at its weakest and the earth itself is also being pulled in the direction of the moon

Sun’s Interaction with Tides 1. Spring Tides (they do not have anything to do with the season Spring)  are especially strong tides  Occur when the Earth, Sun, and the Moon are in a line.  The gravitational forces of the Moon and the Sun both contribute to the tides.  Spring Tides occur during the full and new moon

2. Proxigean Spring Tides  Rare and unusually high tide  Occurs when the moon is both unusually close (proxigee) to the Earth and in the new moon phase (when moon is between the sun and the earth)  Occurs at most once every 1.5 years

3. Neap Tides  Very weak tides  Occur when the gravitational forces of the moon and the sun are perpendicular to one another (with respect to the Earth)  Neap Tides occur during quarter moons

Types of Tides

Diurnal Tides  These tides have 1 high and 1 low tide per tidal day  Found in parts of the northern Gulf of Mexico and Southeast Asia

Semi-diurnal Tides  These tides have 2 high and 2 low tides per tidal day  Found on the Atlantic coasts of the United States and Europe

Mixed Tides  These tides have a high high tide, a low high tide, a high low tide, and a low low tide  Found around the west coast of Canada and the United States