The hydrosphere includes all of Earth's water found in oceans, lakes, rivers, soil, groundwater, and the atmosphere. It is made up of water constantly circulating through the hydrologic cycle between these different reservoirs. The hydrosphere provides an important habitat for many organisms and helps regulate the climate by storing and transferring heat energy around the planet. It also plays a crucial role for life by providing the water that makes up living cells and allows biochemical reactions to occur.

1. EARTH’S HYDROSPHERE

2. hydrosphere, Discontinuous layer of water at or near the Earth’s surface. It includes all liquid and frozen surface waters, groundwater held in soil and rock, and atmospheric water vapor. Virtually all of these waters are in constant circulation through the hydrologic cycle. Although the components of the hydrosphere are undergoing continuous change of state and location, the total water budget remains in balance. The components of the hydrosphere have been seriously affected by the water-polluting activities of modern society. Hydrosphere

3. Hydrosphere Cycle The hydrologic cycle is a conceptual model that describes the storage and movement of water between the biosphere, atmosphere, lithosphere, and the hydrosphere (see Figure 8b-1). Water on this planet can be stored in any one of the following reservoirs: atmosphere, oceans, lakes, rivers, soils, glaciers, snowfields, and groundwater.

4. The hydrosphere is often called the "water sphere" as it includes all the earth's water found in oceans, streams, lakes, the soil, groundwater, and in the air. The hydrosphere interacts with, and is influenced by, all the other earth spheres. [ It is the home for many plants and animals. The ocean serves two main purposes in the climate system. First, it is a large reservoir of chemicals that can contribute to the greenhouse effect in the atmosphere and energy absorbing 90% of the solar radiation which hits the surface. This reservoir changes very slowly limiting how fast the climate can change. Second, it works with the atmosphere to redistribute the energy received from the sun such that the heat in the topics, where a lot of energy is received from the sun, is transferred toward the poles, where heat is generally lost to space. Importance of Hydrosphere

5. Water is a part of living cells Each cell in a living organism is made up of almost 75% water, and this allows the cell to function normally. In fact, most of the chemical reactions that occur in life, involve substances that are dissolved in water. Without water, cells would not be able to carry out their normal functions and life could not exist. Water provides a habitat The hydrosphere provides an important place for many animals and plants to live. Many gases (e.g. CO2, O2), nutrients e.g. nitrate (NO3−), nitrite (NO2−) and ammonium (NH4+) ions, as well as other ions (e.g. Ca2+ and Mg2+) are dissolved in water. The presence of these substances is critical for life to exist in water. Regulating climate One of water's unique characteristics is its high specific heat. This means that water takes a long time to heat up and also a long time to cool down. This is important in helping to regulate temperatures on earth so that they stay within a range that is acceptable for life to exist. Ocean currents also help to disperse heat. Human needs Humans use water in a number of ways. Drinking water is obviously very important, but water is also used domestically (e.g. washing and cleaning) and in industry. Water can also be used to generate electricity through hydropower. The Importance of the Hydrosphere