Transcript THE WATER CYCLE

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BY: Charlie Cowdery
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Precipitation is when rain falls from the
clouds.
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Runoff can come from many things it can
come from mountains, glashiers, lakes,
rivers, and rain.
In physics, chemistry and materials
science, percolation concerns the
movement and filtering of fluids through
porous materials. Examples include the
movement of solvents through filter paper
(chromatography) and the movement of
petroleum through fractured rock. Electrical
analogs include the flow of electricity
through random resistor networks. During
the last three decades, percolation theory,
an extensive mathematical model of
percolation, has brought new
understanding and techniques to a broad
range of topics in physics, materials
science as well as geography.
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On average, the molecules in a glass of water do not have enough
heat energy to escape from the liquid, or else the liquid would turn into
vapor quickly (see boil). When the molecules collide, they transfer
energy to each other in varying degrees, based on how they collide.
Sometimes the transfer is so one-sided for a molecule near the surface
that it ends up with enough energy to escape.
Liquids that do not evaporate visibly at a given temperature in a given
gas (e.g. cooking oil at room temperature) have molecules that do not
tend to transfer energy to each other in a pattern sufficient to frequently
give a molecule the heat energy necessary to turn into vapor.
However, these liquids are evaporating, it's just that the process is
much slower and thus significantly less visible.
Evaporation is an essential part of the water cycle. Solar energy drives
evaporation of water from oceans, lakes, moisture in the soil, and other
sources of water. In hydrology, evaporation and transpiration (which
involves evaporation within plant stomata) are collectively termed
evapotranspiration. Evaporation is caused when water is exposed to
air and the liquid molecules turn into water vapor which rises up and
forms clouds.
Evaporation is the process by which a liquid becomes a gas. It usually
occurs at the surface of a liquid, When water heats up it turns into
vapor wich goes into the sky and forms into a cloud.
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Transpiration is the evaporation of water from
the aerial parts of plants, especially leaves but
also stems, flowers and roots. Leaf surfaces
are dotted with openings called stoma that are
bordered by guard cells. Collectively, the
structures are called stomata.[1] Leaf
transpiration occurs through stomata, and can
be as a necessary "cost" associated with many
processes such as the opening of the pistil and
allowing the diffusion of carbon dioxide gas
from the air for photosynthesis. Transpiration
also cools plants and enables mass flow of
mineral nutrients and water from roots to
shoots.
Mass flow is caused by the decrease in
hydrostatic (water) pressure in the upper parts
of the plants due to the diffusion of water out
of stomata into thetranspiration is directly
related to the degree of stomatal atmosphere.
Water is absorbed at the roots by osmosis, and
any dissolved mineral nutrients travel with it
through the xylem.
The rate of opening, and to the evaporative
demand of the atmosphere surrounding the
leaf. The amount of water lost by a plant
depends on its size, along with the
surrounding light intensity, temperature,
humidity, and wind speed (all of which
influence evaporative demand). Soil water
supply and soil temperature can influence
stomatal opening, and thus transpiration rate.
A fully grown tree may lose several hundred
gallons (a few cubic meters) of water through
its leaves on a hot, dry day. About 90% of the
water that enters a plant's roots is used for
this process. The transpiration ratio is the
ratio of the mass of water transpired to the
mass of dry matter produced; the transpiration
ratio of crops tends to fall between 200 and
1000 (i.e., crop plants transpire 200 to 1000
kg of water for every kg of dry matter
produced).[2]
Transpiration rate of plants can be measured
by a number of techniques, including
potometers, lysimeters, porometers, and heat
balance sap flow gauges.
Desert plants and conifers have specially
adapted structures, such as thick cuticles,
reduced leaf areas, sunken stomata and hairs
to reduce transpiration and conserve water.
Many cacti conduct photosynthesis in
succulent stems, rather than leaves, so the
surface area of the shoot is very low. Many
desert plants have a special type of
photosynthesis, termed Crassulacean acid
metabolism or CAM photosynthesis in which
the stomata are closed during the day and
open at night when transpiration will be lower.
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Condensation is the change of the physical state of aggregation (or simply state) of matter from
gaseous phase into liquid phase.[1] When the transition happens from the gaseous phase into the solid
phase directly, bypassing the liquid phase the change is called deposition, which is the opposite of
sublimation.
Condensation commonly occurs when a vapor is cooled to its dew point, but the dewpoint can also be
reached through compression. The condensed vapor is called a condensate, the laboratory or the
industrial equipment used for condensation is called a condenser.
The science of studying the thermodynamic properties of moist air and the interrelationships between
these in order to analyze, and predict properties by changing in the conditions of moist air is called
psychrometry. The interrelationship can be graphically represented, and prediction carried out
graphically by the psychrometric chart Most people think the water is condensation, but condensation
is only the process of change.
Water vapor that naturally condenses on cold surfaces into liquid water is called dew. Water vapor will
only condense onto another surface when the temperature of that surface is cooler than the
temperature of the water vapor. The water molecule brings a parcel of heat with it. In order to have
condensed, the molecule tranfers its kinetic energy to the atmosphere. When water vapor condenses
into liquid water, the hydrogen bonds form again and release latent heat, which increases the sensible
heat and causes the air temperature to rise. Sensible heat is removed from the air and the temperature
drops when evaporation is occurring and latent heat is converted to sensible heat and the temperature
rises when condensation occurs. When vapor is cooled it it goes down to the ground as due.
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