• 4 months ago
Transcript
00:00hi kids today we will learn important processes involved in water cycle so
00:10let's start there is water on earth everywhere in the air on the ground on
00:20hills under the ground too but this water always keeps on moving and changes
00:27its states that is liquid keeps on changing into water vapors to ice and
00:35ice again to water and that movement of water along with changing states of
00:42water is called water cycle before we actually learn what is water cycle we
00:51will learn about the important process involved in water cycle first is
00:59evaporation when Sun heats up the water in water bodies it changes into water
01:06vapors and move up to the sky
01:13when plants respire or breathe they release water vapor in the air this is
01:21called transpiration both the processes convert water into water vapors
01:35you
01:37water vapor in the air gets cooled down then changes back to liquid form this is
01:45called condensation here is a very good example of condensation a cold glass of
01:54water with tiny droplets of water outside it these droplets of water are
02:00not leaked from the glass so then where did they come from the cold the cold
02:08water inside the glass cools down the air around the glass too so the water
02:15vapors in that air too cools down and when water vapors are cooled down they
02:22again form water and it's called condensation so these droplets around
02:31the cold glass of water is a result of condensation precipitation
02:39precipitation is a process where water falls from the clouds it can be a
02:46rainfall snowfall or hailstorm precipitation occurs when water vapors
02:56in the clouds condenses into water and the clouds get too heavy to hold it
03:03anymore and condensed water falls on earth in the form of rain hail sleet or
03:11snow through precipitation water falls back on earth and gets stored in water
03:19bodies and also some of the water is soaked by plants some is soaked by land
03:26some of the water gets stored as underground water in aquifers and this
03:32is called collection of water and the process of soaking water by the ground
03:40is called infiltration surface runoff when water in ice caps melts it flows
03:49down the hills in the form of streams and rivers it is called surface runoff
04:00now we know all the parts of water cycles
04:06we will learn what is a water cycle in detail in our next assignment now let's
04:15see what is the meaning of the term fresh water we all need water for many
04:22uses and there are many types of sources of water
04:29we need fresh water to drink and most of the earth's water is salt water that is
04:38we can't drink it so there are a number of sources of water on earth but we need
04:46only fresh water and fresh water is naturally occurring water on earth's
04:55surface in ice sheets ice caps glaciers icebergs bogs ponds lakes rivers and
05:05streams and even underground as groundwater the term sweet water is used
05:14to describe fresh water in contrast to salt water which is present in seas and
05:21oceans kids only 2.5% of the total water present on the earth is fresh water and
05:33most of it is in glaciers and ice caps
05:40so our fresh water is very limited and we should take all the possible steps to
05:48use fresh water smartly that is we should not waste water
05:57kids even the fresh water is required to be filtered and treated before we drink
06:03it in our homes water comes from a public water system
06:11for example in Toronto water is moved from Lake Ontario a natural freshwater
06:19source to a human-made water treatment plant where it is filtered cleaned and
06:25treated so that it is absolutely safe to drink and then it is moved to homes
06:33businesses through water supply systems of pipes and pumps so kids today we
06:41learned important processes involved in water cycle and also what is fresh water
06:48and why we should use fresh water smartly now you may go ahead and take a
06:56quiz to learn more bye-bye