ESS SL topic 4.1 Water systems (new syllabus)

Hydrosphere (4.1.1)

The complete system of water on Earth, including oceans, lakes, rivers, groundwater, ice, and water vapor in the atmosphere. For example, it includes both the Arctic ice caps and the Amazon River basin.

Hydrological cycle (4.1.2)

The continuous movement of water on, above, and below Earth's surface through processes like evaporation, condensation, and precipitation. For example, water evaporates from the Pacific Ocean, forms clouds, falls as rain in the Andes Mountains, and eventually returns to the ocean through rivers.

Stores (4.1.2, 4.1.3)

Places where water is held within the hydrological cycle, such as oceans, glaciers, groundwater, and living organisms. For example, Lake Baikal in Russia is the largest freshwater lake on Earth by volume.

Flows (4.1.2, 4.1.4)

Movements of water between different stores in the hydrological cycle. For example, the Amazon River represents a major movement of water from land to ocean.

Transpiration (4.1.4)

The process by which water vapor is released from plants through their leaves. For example, rainforest trees in the Amazon release enormous amounts of water vapor, creating a "flying river" effect.

Sublimation (4.1.4)

The direct transformation of ice into water vapor without passing through the liquid state. For example, snow on Mount Kilimanjaro returns to the atmosphere due to the dry air without melting first.

Evaporation (4.1.4)

The process by which liquid water changes into water vapor. For example, liquid water transforms into gaseous water vapor as it rises from the surface of the Mediterranean Sea, especially during hot summer months.

Condensation (4.1.4)

The process by which water vapor changes into liquid water. For example, water vapor cools to form clouds over the mountains of New Zealand.

Advection (4.1.4)

The horizontal movement of water vapor or water droplets by wind. For example, monsoon winds carry moisture from the Indian Ocean to South Asia.

Precipitation (4.1.4)

Water that falls from the atmosphere to Earth's surface as rain, snow, sleet, or hail. For example, Seattle receives approximately 940 mm of rainfall annually.

Surface run-off (4.1.4)

Water that flows over land after rainfall or snowmelt instead of being absorbed into the ground. For example, heavy rains in urbanized areas of Los Angeles create substantial 'mini floods' due to concrete and asphalt surfaces.

Infiltration (4.1.4)

The process by which water enters soil from the surface. For example, rainwater seeps into forest soils in Finland, replenishing groundwater supplies.

Percolation (4.1.4)

The movement of water through soil pores. For example, water moves through sandy soils in the Sahel region of Africa much faster than through clay soils.

Groundwater flow (4.1.4)

The movement of water beneath the Earth's surface through soil and rock formations. For example, the Ogallala Aquifer provides water across eight U.S. states.

Steady state (4.1.6)

A condition where inputs to a system equal outputs, creating a stable equilibrium. For example, Lake Geneva maintains a relatively stable level with inflows from rivers balancing outflows and evaporation.