when water is kept in a container for few days  their is a dust flim develops on top of water why it forms?
547891
Whe water sit stationary in a container undistured, the surface of the water will have a certain surface tension that act somehow like a piece of paper that can hold certain weight that rest on it. Dust which is basically made up of very light particles will settled on the surface and remains on it since the weight is not enough to overcome the force of the surface tension forming the water surface. However, if u try to add in surfactants such as soap into the water and compare it with just pain water alone, u will notice that the dust film develops faster on the plain water! This is so since soap or detergents acts as a surfactants that can break or reduces the surface tension force of water hence more dust particels can actually break through them and as a results less dust film form on it!!!
974729
Gravity. Water doesn't seek its own level on the Space Station, it forms a ball-shaped blob.
343568
Its not.  What you see on top of water is hydrocarbon polution.  most really deadly polutants such as hexa valent chromium deposit in the river bed or lake floor and continue to contaminate the water for several years.
492491
Water vapor is transparent (for most purposes) and so mere humidity in the atmosphere can't be a cloud. Since clouds don't have motors keeping them in the air, and yet stay there for hours in some cases, they can't be solid, for if they were, they'd fall out of the sky and we'd find cloud bits laying around on the ground. And the same is true for liquid as well. \n\nSo what's a cloud? Mostly, it's very small bits, so small that air currents can keep them in the air. The bits can be solid (eg, ice crystals of which snowflakes are examples), or liquid (eg, little drops of water, of which rain is an example). In either case, enough of these small things begin to look white as light passes thorough them and is reflected and refracted and generally diverted. Kind of like the effect of fine particulate suspensions in water. They are sometimes referred to as milky looking. Indeed, milk is white for a similar reason.\n\nThese are usually formed around dust bits, for real. High humidity (forced by cooling temperatures) produces supercooling (ie, ready to condense, if a trigger can be found). The dust motes provides the trigger. With updraft winds, a condensed drop can grow pretty large. And if it goes high enough, and gets cold enough, the drop can freeze (and thus make hail). If the orignal condensation is sufficiently cold, then water will be added to an ice crystal. With the proper history, such crystals become snowflakes.
501598
Water molecules attract each other. This is called cohesion. \nThe oxygen end of water has a negative charge and the hydrogen end has a positive charge. The hydrogens of one water molecule are attracted to the oxygen from other water molecules. This attractive force is what gives water its cohesive properties.\n\nSurface tension is the name we give to the cohesion of water molecules at the surface of a body of water. It is the reasons that water contracts in drops.\nWhat is happening? Each molecule in the water drop is attracted to the other water molecules in the drop. This causes the water to pull itself into a shape with the smallest amount of surface area, a sphere. All the water molecules on the surface of the bead are 'holding' each other together or creating surface tension.\n\nSurface tension allows water striders to 'skate' across the top of a pond. You can experiment with surface tension. Try floating a pin or a paperclip on the top if a glass of water. A metal pin or paper clip is heavier than water, but because of the surface tension the water is able to hold up the metal.
585225
The chemistry is in the changes in the state of matter & water's properties such as cohesion & adhesion.\n\nWater is evaporated from the earth's surface, rises with warm air masses, cools & condenses on condensation nuclei w/in the upper atmosphere (property of adhesion). Clouds form & continue to build as long as there is updraft (warm rising moist air).\n\nBecause of water's property of cohesion, the tiny water droplets will begin sticking together. When they become too heavy to w/stand the pull of gravity, they will descend & fall as rain.
655206
This has to do w/ the way it forms in clouds.\n\nAs warm moist air rises, it will expand & cool. When it reaches the dew point, it will condense on particulates in the air such as pollen, dust, salts, pollution, etc. This is the formation of a cloud.\n\nThe condensation nuclei described above is the primary source for the shape of the raindrop that may eventually form from the cloud.\n\nAs the water droplets bump into each other, they will begin to stick, growing larger & larger.\n\nWhen wind currents can no longer hold up the droplets, gravity wins the tug-of-war & the droplet will fall.\n\nSome people mistakenly believe that raindrops are "teardrop" shaped. This is not true. They are spherical as they fall through the atmosphere. That is until they hit something.
222634
Tap water evaporates as it sits around.  The additives become more concentrated as the water evaporates but they don't dissipate.  Eventually they "precipitate" as salts and end up as solids in the container.
993848
Water is a very unusual substance. When it becomes a solid and crystallizes. The structure of the ice crystal become less dense and floats. The crystalline structure actually pushes the water molecules away from each other and thus expands. This is very unusual because water is one of the only (if not the only) substance that floats as a solid when it is within its on liquid (if that make any sense). So, in an unconfined area, such as a glass of ice water, you would see that the ice floats and rises above the water. In an confined area, such as a bottle, the Ice has no place to go so it expands the bottle. When you let a little of the ice melt and the is some water in the bottle, the bottle is still under pressure from the ice and the water will come out. To prove this, go ahead and freeze a bottle of water, then let it thaw completely; if there is no ice in the bottle, then the water will not come out. It only come out due to the expansion of the ice.
406921
clouds are just condensted water the water would stick to the bag eg.- fill jar with water put top on and wait a while water particas form a "cloud"
1081964
they are all fases of the water cicle. First the water evaporates (goes from being in a liquid state to being in a gasy state) due to the heat coming from the sun, the water vapor rises up in the air and condensates (takes a more dense state but still remains being water vapor) then after a lot of water vapor is concentrated (humidity) a cloud forms and it gets bigger and bigger as more and more water vapor concentrates until the amount of humidity is to large and the water vapor turns into water and precipitates wich would conclude the cicle in this last fase ,wich goes by the name of precipitaion, and then to start all over again.
751012
Clouds are formed essentially by water vapours.The uppermost layer of waterbodies like sea,river,ponds etc(specially sea) are in the process of evaporation always.now water vapour is a gas and due to the fa that the surface of the waterbodies and the earth is hotter,the watervapour expands its volume.As you must be knowing density of an object is its mass divided by volume.Mass being constant,if volume increases density decreases and the water-vapour getting lighter goes up.There the temperature being less ,the water vapour condenses into water-droplets and floats as clouds,
30608
Clouds are formed when warm moisture laden air is forced upwards either by a physical obstruction such as a hill/mountain or by being heated by the ground/sun.\nAs it rises it cools, and cold air can hold less moisture than warm air, so the vapour condenses out into droplets that form our clouds.\n\nFog is caused when moisture laden air is cooled by contact with the ground or water, it gets colder and colder until any moisture condenses out.  Fog forms as a layer as the air above it tends to be warmer due to rflected heat from the sun and also becauseof the lack of wind to stir the two layers together.  This is often referred to as an inversion.
1058208
definitely not true. it just appears that way because it hits the water and disperses before you can really notice it but if you watch its there.
472454
During winter the water at the surface of lake or pond gets cooled.\n\nDue to cooling density of water increases; denser water\ngoes down, while the relatively hot water comes up. This is convection.\n\nBut water has a peculiar property that below 4 degree C it becomes less dense.\n\nTherefore when the surface temperature is 4degree and below, the water at the surface cannot go down. Hence convection of water is stopped. \n\nThe temperature increases relative to water surface.  If the temperature of the water surface reaches freezing temperature, ice is formed on the surface and the freezing takes place from top to bottom.\n\nThus lives of water living creatures are saved from freezing.
174421
A contrast of saltiness in water (halocline) can form in the ocean, because there is a tendency for less dense fresher water to float on top of denser saltier water. This happens for example when a river (fresh water) discharges into the ocean.\nThermocline forms when water at the surface of an ocean or lake is heated up, while the water below stays cool
630793
Clouds are formed by water vapor. And high pressure can hold more water vapor. So when vapor moves into a low pressure system it condenses and and forms clouds and those clouds precipitate when the system cant hold no more water vapor