Hydrosphere Exercise Solutions | KalviGavani

The hydrosphere is the total water system on Earth. Its components include: 1. Oceans and seas (97% — salt water) 2. Ice caps and glaciers (~2% — frozen freshwater) 3. Groundwater (0.7% — water below the surface) 4. Surface water (rivers, lakes, ponds — 0.01%) 5. Atmospheric water (water vapour, clouds — 0.001%)

| Feature | Spring Tide | Neap Tide | |---|---|---| | When | Full moon and new moon | First and third quarter moons | | Alignment | Sun, Moon, Earth in line | Sun, Moon at right angles | | Tidal range | Maximum | Minimum | | High tide | Highest | Lower than spring tide | | Low tide | Lowest | Higher than spring tide |

Ocean currents are continuous, directed movements of ocean water driven by wind, Earth's rotation, temperature, and salinity differences. Warm currents: Gulf Stream (North Atlantic), Kuroshio Current (North Pacific) Cold currents: Labrador Current (North Atlantic), Benguela Current (South Atlantic)

Salinity is the total amount of dissolved salts in ocean water, expressed in parts per thousand (‰). Average ocean salinity is about 35‰. Factors affecting salinity: 1. Evaporation: Higher evaporation → higher salinity (subtropics) 2. Precipitation: Higher rainfall → lower salinity (equator) 3. River inflow: Large river input → lower salinity (Bay of Bengal) 4. Ice melting: Melting ice → lower salinity (polar regions)

The ocean floor has distinct features from the coast to the deep ocean: 1. Continental Shelf (0-200 m): - Gently sloping, shallow area bordering the continent - Rich in marine life and mineral resources (petroleum, natural gas) - Width varies: wide in passive margins (East Coast of India), narrow in active margins 2. Continental Slope (200-3000 m): - Steep descent from the shelf edge to the deep ocean floor - Marks the boundary between continental crust and oceanic crust 3. Continental Rise: - Gently sloping transitional area between the continental slope and the abyssal plain - Composed of sediment deposited by turbidity currents 4. Abyssal Plain (3000-6000 m): - Flat, vast, featureless deep-sea plain - Covers about 76% of the ocean floor - Covered with fine sediment (ooze) 5. Mid-Oceanic Ridge: - Continuous underwater mountain range running through all oceans - Longest mountain system on Earth (~65,000 km) - Site of seafloor spreading and volcanic activity 6. Seamounts and Guyots: - Seamounts: Underwater volcanic peaks rising above the abyssal plain - Guyots: Flat-topped seamounts (eroded by waves before subsiding) 7. Trenches (6,000-11,000 m): - Deepest parts of the ocean, found near island arcs - Mariana Trench (11,034 m) is the deepest - Formed by subduction of one plate under another

Causes of Ocean Currents: 1. Wind: Trade winds and westerlies push surface water in their direction 2. Coriolis effect: Earth's rotation deflects currents to the right in the Northern Hemisphere and to the left in the Southern Hemisphere 3. Temperature differences: Warm water rises and cold water sinks, creating convection currents 4. Salinity differences: More saline water is denser and sinks, less saline water rises 5. Gravity: Pulls denser (cold/salty) water downward Types of Ocean Currents: Warm Currents (flow from equator towards poles): - Gulf Stream: Warm current from Gulf of Mexico to North Atlantic - North Atlantic Drift: Extension of Gulf Stream warming NW Europe - Kuroshio Current: Warm current east of Japan - Agulhas Current: Warm current along SE coast of Africa Cold Currents (flow from poles towards equator): - Labrador Current: Cold current from Arctic along east coast of Canada - Canary Current: Cold current along west coast of Africa - Benguela Current: Cold current along west coast of southern Africa - Oyashio Current: Cold current from Arctic along east coast of Russia Effects of Ocean Currents: - Warm currents warm the climate of adjacent coastal areas (e.g., North Atlantic Drift keeps NW Europe warm) - Cold currents cool the climate (e.g., Benguela Current keeps Namibia cool) - Warm and cold currents meeting create fog and rich fishing grounds (e.g., Grand Banks off Newfoundland)

Causes of Tides: Tides are caused primarily by the gravitational pull of the Moon and, to a lesser extent, the Sun on the Earth's ocean water. Moon's influence (primary): - The Moon's gravitational pull creates a bulge in the ocean on the side facing the Moon (high tide) - A second bulge occurs on the opposite side due to centrifugal force - The Moon completes one revolution around Earth in about 27.3 days Sun's influence (secondary): - The Sun also exerts gravitational pull on ocean water, but about 46% of the Moon's effect - When Sun and Moon are aligned, their forces combine (spring tide) - When Sun and Moon are at right angles, their forces partially cancel (neap tide) Spring Tides vs Neap Tides: | Feature | Spring Tide | Neap Tide | |---|---|---| | When | Full moon, new moon | First quarter, third quarter | | Alignment | Sun, Moon, Earth in line | Sun, Moon at right angles | | Gravitational force | Combined (maximum) | Partially opposed (minimum) | | Tidal range | Maximum | Minimum | | High tide | Highest | Lower | | Low tide | Lowest | Higher |