Moisture, Humidity and the Water Cycle

Relative humidity is defined as the ratio of the amount of water vapor in the air to the maximum amount of water vapor the air could hold at that temperature, expressed as a percentage.

Precipitation is the general term for any form of water (liquid or solid) that falls from the atmosphere to the Earth's surface.

Evaporation, condensation, and precipitation are all stages of the water cycle. Salination is the process of increasing salt content in soil or water, which is not a part of the water cycle.

Transpiration is the loss of water from a plant in the form of water vapor. Water is absorbed by roots from the soil and transported as a liquid to the leaves via xylem. In the leaves, small pores allow water to escape as a vapor.

• Globally water occupies a major portion. Water constitutes 96.5 % on the earth and rest is land. Of the total water content fresh water contributes a very little portion of 2.5%. Fresh water sources include:
  
• Groundwater - water found in shallow aquifers beneath the earth's surface. This water is generally found at depths up to around 2,000 feet deep.
  
• Precipitation: It is nothing but the rain water which is an important source of fresh water. In fact it is the purest natural source of fresh water.
  

• A rain gauge is a little cylindrical container that collects rainwater falling into it to measure the rainfall during a particular period.
• Certain conditions are needed to be fulfilled for accurate measurement of rainfall viz water should not enter into the rain gauge from any source other than direct rainfall and the rain gauge instrument has to be kept at a certain height. 

• Mawsynram located in Meghalaya, India receives 11871 mm of annual rainfall which is highest in the world thus option D is the correct answer.
• Cherrapunjee is located only  15 km away from Mawsynram is in second place in terms of the amount of rainfall.

Absolute humidity is the total amount of water vapor present in the air. In other words, the weight of water vapor per volume of air is referred to as the absolute humidity. It is usually expressed as grams of water vapor per cubic meter of air. Absolute humidity varies with the expansion or contraction of air, even though the amount of water vapor is constant.

Convectional rainfall occurs when surface of the earth is heated up by the sun. The warm surface also heats up the air. As air rises it cools down and begins to condensate. Further rising and cooling causes a large amount of condensation to occur and rain is formed. Conventional rainfall usually occurs in the equatorial region.

Rainbow is caused by reflection, refration and dispersion of light in water droplets resulting in a spectrum of light appearing in the sky. It is a meterological phenomenon. It is caused in the presence of sunlight. It appears in the section of sky which is directly opposite to the sun.

B.  Latent Energy

 Latent heat is the energy absorbed by or released from a substance during a phase change from a gas to a liquid or a solid or vice versa.  If a substance is changing from a solid to a liquid, for example, the substance needs to absorb energy from the surrounding environment in order to spread out the molecules into a larger, more fluid volume.  If the substance is changing from something with lower density, like a gas, to a phase with higher density like a liquid, the substance gives off energy as the molecules come closer together and lose energy from motion and vibration.

Absolute
humidity is the actual amount of water vapour present in air. It is expressed
as grams of moisture per cubic meter of air. It is calculated by finding the
mass of water vapor in an area and dividing it by the mass of air in the same
area. Absolute humidity may range from 0 gram per cubic meter in dry air to 30
grams per cubic meter when the vapour is saturated at 30 $^oC$. As the
temperature of air increase, humidity also increases.

The
phenomenon by which gaseous molecules convert from gaseous state to liquid
state is called condensation. It is the process by which water vapor in the air
is changed into liquid water. Condensation is responsible for the formation of
clouds. That’s why it is crucial to the water cycle. These clouds produce
precipitation which is the primary route for water to return to the Earth’s
surface through rain. Condensation is the opposite of evaporation.

Humidity means the amount of water vapor present in the air. Time, place and temperature play important role in determining humidity. Amount of humidity changes with season and weather variation. Nearness to a water body,i.e, place plays an important role in determining humidity and lastly the moisture-holding capacity of air increases with increasing temperature.

Relative
humidity is expressed as the amount of water vapor in the air as a percentage
of the total amount that could be held at its current temperature. Absolute
humidity is the measure of water vapor in the air, regardless of temperature.
Relative humidity is cited in weather forecasts. It affects how we feel
temperature. That’s why relative humidity is important.

The water vapor is one of the most variable gases in the atmosphere  which is present in small amount but is none the less very important. Water vapor plays an significant role in the insulating action of the atmosphere. The moisture holding capacity of the air varies in the direct proportion to its temperature. In other words the higher the temperature of the air,  the larger the capacity to hold moisture and vice versa. 

The
droplets of water deposited on any cool surface by condensation of water vapour
in atmosphere are known as dew. When temperature drops and objects cool down,
dew is formed. The temperature at which dew forms is called the dew point. Location,
weather, and time of day affect the dew point. Dew is more likely experienced
by the humid areas than arid areas. It is mostly formed at night.

When the moisture saturated air comes across barriers such as mountains, it is forced to ascend and as it rises. Then condensation takes place and rainfall occurs. This type of rainfall is called relief rain or orographic rain. 

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When
cloud particles become too heavy to remain suspended in the air, then condensed
water vapor falls back to the Earth in various forms. This process is called as
precipitation. Precipitation is very important for the life forms on the Earth.
The different forms of precipitation are:

Through the continuous process of condensation, the condensed particles grow in size. They are called water droplets or ices droplets. Due to the force of gravity, these droplets are formed are forced to come down and it is called precipitation. Precipitated moisture falling on the ground takes various forms it can be rain, drizzle, snow, sleet, hail, etc.

Fog consists of visible cloud water droplets or ice crystals suspended in the air at or near the Earth's surface. Fog can be considered a type of low-lying cloud and is heavily influenced by nearby bodies of water, topography, and wind conditions. In turn, fog has affected many human activities, such as shipping, travel, and warfare.

Cloud has been defined as a visible aggregation of minute water droplets or ice particles in the air, usually above the general ground level. Clouds are the most important form of suspended water droplets caused by condensation. Clouds are generally formed because of adiabatic cooling resulting from the upward movement of air.

Humidity,

In a cyclone, the winds from all directions converge at the centre. Air with different temperature meets at the center. The cold air pushes the warm air upward which gets cool as it moves up and precipitation occurs.  So rainfall due to cyclones and depression is termed as cyclonic rainfall.

Tiny drops of water that form on cool surfaces at night, when atmospheric moisture gets deposited on the cool surface, is called dew. Thus option B is correct.

• A land breeze is a breeze blowing towards the sea from the land, at night, owing to the relative warmth of the sea. It blows only in the night and not for 24 hours, thus option D is the answer as the statement is wrong.
• Rest statements are true, hence cannot be the answer.

Evaporation, condensation, and precipitation are fundamental processes of the water cycle. Salination refers to the accumulation of salts in soil or water, which is distinct from the water cycle.

Villages in India commonly rely on groundwater sources such as wells and tubewells for their water supply.

In manufacturing processes, water is used to generate electric power, to make steam for processing and cleaning, to cool or control process temperature, to rinse, to dilute food, and to formulate products containing water. 

Precipitation is the primary mechanism by which water is transferred from the atmosphere back to the Earth's surface.

The
process by which moisture is carried through plants from roots to small pores
on the underside of leaves, where it changes to vapour and is released to the
atmosphere is known as transpiration. 

Prolonged reduction of ground-water supplies can have a devastating effect on a farmer’s crop yields. If a drought occurs soon after seeding, plants may fail to germinate; and during the later stages of development, a drought can cause entire crops to wither.

Precipitation in the form of solid particles of snow is known as snowfall. In high latitudinal and temperate regions, snowfall occurs at the mean sea level while in tropical areas, snowfall occurs at place located higher than the snowline altitude.

70.8% part of the earth's surface is full of water. The distribution of this water is very uneven. At some places, the water storage is limited while it is ample at other place.

When water falls in the solid or liquid state from the clouds to ground, it is
known as precipitation. Snow, hailstones, rainfall are the major forms
of precipitation.

When
the temperature in the atmosphere falls below the freezing point, water
vapour directly turns into snowflakes. This process is known as sublimation.

When water falls in the solid or liquid state from the clouds to ground it is called precipitation. Snow, hailstones, rainfall are the major forms of precipitation.

The process by which water vapour in the atmosphere changed into liquid water is called condensation. As the atmospheric conditions change, we see change in the forms of condensation.

When the saturated air his obstructed by land form barrier such as mountains, it is forced to ascend and as it rises, it expands and temperature falls. As a result, condensation takes place and rainfall occurs. This type of rainfall is called as relief rain or orographic rainfall. 

In orographic rainfall, the windward slope of the mountain receives maximum rain and the leeward slope remains generally drier and is known as the rain shadow area.

When
the condensation or solidification of the water vapor in the atmosphere
occurs near the earth's surface, then  we can see fog, dew, frost etc. 

As hailstones are heavy, they fall towards the ground, but because of the frequent upward flow of air, they are repeatedly taken upwards. Here a new layer of snow encapsulates the hail. This happens quite a few times. Hence concentric layers are formed while the hail grows in size.

Because of the upward movement of air, the water droplets go to higher altitude and solidification of these droplets occur and hailstones are formed.

The precipitation where hail occur with rainfall, that type of precipitation is called as hail showers. Because of hail, crops may get destroyed and loss of life and property may also occur.

Hail do not occur in cold zones because of lack of upward flow.

Rain shadow area is associated with orographic rainfall. When the saturated air is obstructed by land form barrier such as mountain, it forced to ascend and as it rises, it expands and temperature falls. As a result, condensation takes place and rainfall occurs. In this type of presentation, the windward slope of the mountain receives maximum rain and the leeward slope remains generally drier and is known as the rain shadow area.  

Specific air formation when the pressure at an area is less than the surrounding regions. This is called cyclone. Air from the surrounding region comes towards the center of the cyclone and starts moving upwards.

In
equatorial areas, the surface gets heated because of the sun's heat and
the air near it also gets heated. As it gets heated, it spreads and
becomes lighter and moves upwards.

Winds
coming from lakes or seas are moisture-laden. They are obstructed by
the high mountain ranges coming in their way. They start going upwards
along the slope of the mountains, the temperature of these winds drop
and condensation occurs and rainfall takes place. Thus because of the
obstruction of the mountains, this type of rainfall occurs.

Increases as the temperature increases,

While water exists in many forms, rain is the primary source that replenishes surface water and groundwater on Earth.

The water cycle describes how water evaporates from the surface of the earth, rises into the atmosphere, cools and condenses into rain or snow in clouds, and falls again to the surface as precipitation.

Acid rain is caused by a chemical reaction that begins when compounds like sulfur dioxide and nitrogen oxides are released into the air. These substances can rise very high into the atmosphere, where they mix and react with water, oxygen, and other chemicals to form more acidic pollutants, known as acid rain.

Precipitation is any type of water that forms in the Earth's atmosphere and then drops onto the surface of the Earth.

The rain that falls from clouds but freezes before it reaches the ground is called sleet or ice pellets.

Snow is precipitation that falls in the form of ice crystals

Hail  forms when very cold water droplets freeze, or turn solid, as soon as they touch things like dust or dirt

Water vapor in the atmosphere is visible as clouds and fog.

It forms mist. It is a phenomenon caused by the small water droplets of water suspended in the air. When the warm moist air meets the sudden cooling, mist is formed.

The
amount of water vapor in the air is known as humidity. It can make hot
temperatures even more unbearable than they already are. It affects both
weather as well as climate. It also affects global climate change. Both low
humidity as well as high humidity is harmful for us. Humidity is of two types:- Absolute humidity and Relative humidity.

The
process by which water continually changes its form and circulates between oceans,
atmosphere and land is known as water cycle. In the water cycle, water from
oceans, lakes, swamps, rivers, plants can turn into water vapour. Water vapour
condenses into millions of tiny droplets that form clouds. Clouds lose their
water as rain or snow, which is called precipitation. Precipitation is either absorbed
into the ground or runs off into rivers. Plants take up the water that was absorbed into the ground. Plants lose water from their surfaces as vapour that goes back into the atmosphere. Water that runs off into rivers flows into ponds,
lakes, or oceans where it evaporates back into the atmosphere. This cycle continues.

Vernal pools, also called vernal ponds or ephemeral pools, are seasonal pools of water that provide habitat for distinctive plants and animals. 

A  vernal pool basin will experience inundation from rain/precipitation, followed by desiccation from evapotranspiration. These conditions are commonly associated with a Mediterranean climate. Most pools are dry for at least part of the year and fill with the winter rains, spring snowmelts, and rising water tables. Some pools may remain at least partially filled with water over the course of a year or more, but all vernal pools dry up periodically.

The state of atmosphere over an area at any point of time is known as weather. It is the state of the atmosphere over short periods of time. Weather can change from hour to hour, day to day, month to month or even year to year.

Following are the major elements of weather: -

1. Temperature
2. Pressure
3. Humidity
4. Precipitation
5. Wind

• Weather is the state of the atmosphere at a particular place and time. Temperature, humidity, and visibility are the atmospheric phenomena hence part of the weather.
• Sunlight is independent of the atmosphere, thus option D is correct.

Cover
of clouds in portion of the sky visible from the observation point is known as
cloud cover. Weather observer or meteorologists estimates the amount of cloud
cover in sky. Cloud cover is an important factor which decides the weather of
an area. The amount of cloud cover in the sky is measured in units called oktas
or eight for meteorological purposes. Each okta represents one eighth of the
sky covered by cloud.

The
process of changing of water from the liquid state to the gaseous state is
called evaporation. It occurs every day in natural and man-made environments.
It occurs most often around the areas which are situated near water bodies. It
is the most important process in case of water cycle because the water from
water bodies goes into atmosphere through the process of evaporation. The rate
of evaporation increases with the increase in the temperature.

The
amount of water vapor in the air is known as humidity. It can make hot
temperatures even more unbearable than they already are. It affects both
weather as well as climate. It also affects global climate change. Both low
humidity as well as high humidity is harmful for us. Humidity is of two types:-
Absolute humidity and Relative humidity.

Hail
is a small ball of ice in the atmosphere, especially at night. It is a result
of precipitation. It is produced by intense thunderstorms when snow and rain
coexists. As the snowflakes fall, liquid water freezes onto them. It forms ice
pellets that continue to grow as more droplets accumulate. When the ball of ice
becomes so large and heavy, they fall as hailstones.

Cirrus, cumulus, and stratus are the types of cloud. Cirrus clouds are very thin and white in colour. They are formed of ice crystals and give a feathery appearance. They are the highest clouds. Cumulus clouds are generally dense and with sharp outlines, developing vertically in the form of rising mounds, domes or towers, of which the bulging upper parts often resemble a cauliflower. Stratus clouds resemble fog and made up of almost equal layers. Occasionally, they are broken into patches separated by blue sky by the incoming wind. Stratus clouds are grey in colour. 

The
particles of condensed moisture held in suspension close to the surface of the
earth are known as mist. They form at lower density as compared to fog. Their
visibility is more than 1,000 meters. They are quicker to dissipate. They can
rapidly disappear with even slight winds. Mist is what we see when we see our
breath on a cold day.