Hydrosphere - class-VI

Neap tides occur when the sun and moon are at right angles relative to the earth, causing their gravitational forces to partially cancel each other out, resulting in lower high tides.

Tides are the periodic rise and fall of sea levels caused by the gravitational forces exerted by the moon and the sun, and the rotation of the earth.

Spring tides occur when the earth, moon, and sun are aligned, causing their gravitational forces to combine and produce higher high tides and lower low tides.

Neap tides occur during the first and third quarters of the moon phase, when the sun and moon are at right angles to the earth.

The variation between spring and neap tides is evidence that both the sun and the moon exert gravitational influence on the earth's oceans.

While the sun also exerts a gravitational pull, the moon is the primary driver of tides due to its proximity to the earth.

The hydrosphere encompasses all water found on, under, and over the surface of the earth, including oceans, lakes, and rivers.

The continental shelf is the shallow, submerged extension of the continent that extends from the shoreline to the shelf break.

Ripples are the instant effect of wind on water and they die down as quickly as they form, as the surface tension of the water dampens their efforts.

Waves always travel in the same direction as the wind is blowing: if the wind changes then the waves change with it. Wave size is determined by the strength of the wind, the length of time it has been blowing and the distance it has blown over or the ‘fetch’.

When strong winds blow for longer than a few hours, it gives the water sufficient energy that it then takes on a character of its own. This character and movement is known as swell, and it will march across open areas of water independent of the wind.

With 33.7% salinity, the Dead Sea is one of the world's saltiest bodies of water. The Dead Sea is landlocked and in the lowest valley on earth. All the minerals of the surrounding countryside get washed into one pool, which in turn gets baked by the sun. This concentrates the salts so much that the Dead Sea is 10 times as salty as the ocean.

Rivers are the primary source of freshwater for human use and ecosystems, as they collect runoff from precipitation.

Deep sea sediments are largely composed of the remains of microscopic organisms (like foraminifera and diatoms) that settle on the ocean floor.

Wind blowing over the surface of the ocean creates friction, which transfers energy to the water and generates waves.

Approximately 71% of the Earth's surface is covered by water, which constitutes the hydrosphere.

The most abundant dissolved ions in seawater are sodium, chloride, magnesium, sulfate and calcium. Its osmolarity is about 1000 mOsm/l.