Introduction to Part Two of the hydrosphere discussion focusing on oceans, rivers, streams, ice, and the atmosphere.
Presented image of Chopu, a surf spot illustrating the immense power and size of ocean waves.
Water is heavy; example of a cubic meter of water weighing 2,000 pounds, comparable to a car.
Discussion on the impact of hurricanes on coastal communities, emphasizing water movement and risks associated.
Northern Hemisphere Surface Currents: Large rotating masses of water move clockwise; includes cold currents along the California coast.
Southern Hemisphere Surface Currents: Rotating counterclockwise, impacting ocean dynamics differently between hemispheres.
Relationship between wind regimes and water currents established.
Example from California: offshore winds blow surface waters away, allowing deeper nutrient-rich waters to rise.
Summary of upwelling:
1. Winds blow surface waters offshore.
2. Upwelling of nutrient-rich deep waters replaces displaced surface waters.
3. Phytoplankton thrive in nutrient-rich waters, leading to a chain of larger marine organisms.
Conclusion: Upwelling supports rich marine biodiversity along the California coast.
Example from East Coast (Florida): Warm equatorial waters move northward and become saltier and denser, sinking to depth.
Summary of downwelling:
1. Warm water evaporates, increasing salinity.
2. Increased salinity leads to increased density, causing sinking.
Highest and lowest tides occur when the Earth, Moon, and Sun are in alignment (new/full moons).
During alignment, gravitational pull creates tidal bulges, leading to extreme tides.
Weak tides occur when the moon is at a 90° angle relative to the Earth and Sun (first/third quarter moons).
Waves are primarily generated by wind, not gravity.
Key variables for wave formation are: wind speed, consistency, duration, and surface area over which wind blows.
Ocean waves are generally larger than lake waves due to greater surface area.
Headlands: Areas of high wave energy that erode land.
Coves: Areas of reduced wave energy where sediment is deposited.
Result: Coastlines tend to straighten over time as headlands erode and coves accumulate sediment.
Storm surge is a significant outcome of hurricanes, often leading to flooding in coastal areas.
Increasing global temperatures correlate with increased intensity and frequency of hurricanes.
Summary of hurricane dynamics:
1. Increased frequency of intense hurricanes; the 100-year storm becomes more common.
2. Emergence of new, more intense storms as global climate changes.
3. Sea level rise exacerbates hurricane impacts.
Understanding these dynamics is essential as we continue discussing the hydrosphere, focusing on freshwater systems and the cryosphere in future sessions.