Water Bodies — Oceans, Rivers & Lakes

• Hydrosphere — all water on Earth (97% saltwater in oceans; 3% freshwater).
• Five oceans and their features.
• Ocean movements: waves, tides, ocean currents.
• Types of water bodies: rivers, lakes, glaciers, groundwater.
• Water cycle — evaporation → condensation → precipitation → runoff.

The five oceans (largest to smallest)

Ocean movements

Waves:

• Caused by wind blowing over ocean surface.
• Energy moves, water doesn't travel forward.
• Tsunamis = giant waves caused by undersea earthquakes.

Tides:

• Rise and fall of sea level due to gravitational pull of the Moon (mainly) and Sun.
• High tide: water level rises (Moon pulls water towards it).
• Low tide: water level falls.
• Spring tides: Moon + Sun aligned → very high tides (new moon/full moon).
• Neap tides: Moon + Sun at right angles → moderate tides.

Ocean currents:

• Large streams of water flowing in fixed paths through the ocean.
• Warm currents flow from equatorial regions towards poles (e.g., Gulf Stream).
• Cold currents flow from poles towards equator (e.g., Labrador Current).
• Influence climate: warm currents → warmer nearby coasts; cold currents → fog, fish-rich waters.

Freshwater bodies

Water cycle

Evaporation (ocean/land) → Water vapour rises → Condensation (clouds form)
→ Precipitation (rain/snow) → Runoff (rivers) / Infiltration (groundwater)
→ Back to ocean → Repeat

Sun provides energy; gravity drives runoff.

• Name the five oceans in order of size.
• What causes tides? What is the difference between spring tides and neap tides?
• What are ocean currents? Give one example each of warm and cold current.
• Name four types of freshwater bodies.
• Describe the water cycle in 4 steps.

Open the Practice tab for graded questions on Water Bodies.