Clouds 2011

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Vertically

Developed

CloudsB.S(Hons.) 4

th SemesterRabia ... Rafia … Rbiya

Atiqa

Table of Contents1) Definition of clouds …032) Formation of clouds …063) Classification of clouds …104) Vertically Developed clouds …165) Categories …19

1) Cumulus clouds …201) Hmulis …232) Fractus …263) Congestus …284) Castellanus …29

2) Cumulonimbus clouds …311) Cumulonimbus Incus …362) Cumulonimbus Mammatus …383) Cumulonimbus Calvus …41

6) References …44

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Definition “A visible collection of CONDENSED tiny water droplets and ice crystals suspended in the atmosphere.” Clouds can be in variety of forms. Some are found at high elevation but other are near the ground relatively

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All the weathering phenomenon occurs due to the clouds… ranges within the troposphere.

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Formation of Clouds Water is known to exist in three forms:

Clouds, snow and rain are all made up of some form of water.

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Generally produced by atmospheric motion with upward component cools the air.

Clouds form when temperature is below the dew point.

When air blows over the colder surface.

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By orographic uplift of air near the mountainous terrain.

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Air parcel will rise up naturally if the air within it is warmer than the surrounding air by convection.

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Classification of theClouds

Clouds are classified into a system that uses “Latin” words to describe their appearances.They are define on the basis of their “Heights”. This was done by an English chemist “Luke Howard” in 1803.

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LATIN NAMES ENGLISH NAMES

Cirrus Curl of hair

Stratus Layer like

Cumulus Heap

Nimbus Rain

HOWARD divided them into 4 categories using Latin names as:

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They are further divided into 4 groups having 10 types of the clouds:

The first 3 groups are differentiating by their heights.The fourth group contains thick clouds as they are NOT describe on the basis of heights level from grounds.

GROUPS HEIGHTS

High Clouds 5-13km

Middle Clouds 2-7km

Low Clouds 0-2km

Vertically Developed Clouds ---

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STRATUS CIRRUS

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CUMULUS

NIMBUS

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SUB-GROUP

• Cirrus• Cirrostratus• Cirrocumulus

• Altostratus• Altocumulus

• Stratus• Stratocumulus• Nimbostratus

• Cumulus• Cumulonimbus

High Clouds

Middle Clouds

Low Clouds

Vertically Developed

Clouds

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Vertically Developed

Clouds They are due to unstable atmospheric conditions.Height can range up to 12000m.Generated most commonly either by thermal convection or frontal lifting.Releasing incredible amount of energy to condensed the water vapor within the clouds.

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They are generally not the sign of calm weather.

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CategoriesVertically developed clouds are more conveniently divided into 2 categories as:

1)Cumulus Cloudsi. Cumulus Humilis Cloudsii. Cumulus Fractus Cloudsiii. Cumulus Congestus Cloudsiv. Cumulus Constellus Clouds

2)Cumulonimbus Cloudsv. Cumulonimbus Incus Cloudsvi. Cumulonimbus Mammatus Cloudsvii. Cumulonimbus Calvus Clouds

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1- Cumulus Clouds

They look like white ball of cotton _ isolated in sky.Are sign of pleasant weather.They have flat bottoms and lumpy tops.Top often is in the form of towers--- shows the limit of rising air.

Rising air is associated with high relative humidity.Generally they are formed by convection resulting from solar heating in summers.Over open lakes in autumn and winters.

Formation :

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Rain Variation

For 15th to 24th March-2011

By Cumulus

clouds

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They are found as low as 330ft.

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Humilis stands for “HUMBLE.”Generally have flattened bases and slight vertical development.Mostly rises up to 5-8km.

Once the thermals rise above the surface, the potential for cloud development increases.At the condensation level, the relative humidity of the thermal air will be around 100 percent (saturated).

Formation :

Cumulus Humilis

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Between each cumulus humilis, the air descends slowly to replace the rising thermals

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As a result, the cloud -field can look very regularl-ySpaced.

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Cumulus FractusCumulus clouds that appear in irregular fragments, as if they had been shred or torn.

Always appear in association with other clouds.For a short time before, during and a short time after precipitation.

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They can form  in fair weather as rising pockets of warm air rise and condense into these proto-clouds

Cumulus fractus on not-so-fair days, too, as they "shredded" by larger cumulonimbus cloud after a rain storm

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Cumulus Congestus

Congestus is Latin for "piled-up".When a humilis cloud grows vertically it turns into a congestus cloud. These clouds may produce abundant show-ers

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It stands for “Castle-like”.It displays multiple towers arising from its top, indicating significant vertical air movement

Cumulus Castellanus

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2- Cumulonimbus Clouds

These are more vertically developed than fair weather cumulus and have tops that can reach up to 39,000 feet (12,000m).  These are fueled by strong updrafts that transfer air up through the atmosphere. 

These clouds are named because they are puffy ("cumulo") and because they often are dark clouds which cause rainstorms ("nimbus").Cumulonimbus clouds are characterized as tall, dense clouds

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Cumulonimbus clouds designs its formation mostly during the afternoon time, as this the time when the earth surface gets heated up. Cumulonimbus clouds are usually seen in the shape of mushroom.

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Common types of Clouds

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Cumulonimbus Cloud Over Africa Image Credit: NASA March 24, 2011

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Rain Form

-a-tion

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Cumulonimbus Incus

Incus stands for “Anvil”.A mature cumulonimbus incus is definitely the “King of Clouds”, and sometimes reaching 60,000 feet in tropical and subtropical areas. Formation always be regarded as a significant aviation hazard because of :

“the powerful air currents involved in its formation and the potentially damaging effect of the large hailstones it may produce.”

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Cumulonimbus Mammatus

They look like “BAG.”Mammatus is one of the most spectacular and distinctive of all cloud formations.

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During a thunderstorm, warm, moist updrafts rise to the top of the troposphere. Here the temperature levels off and the air stabilizes. This causes the rising cloud to expand horizontally over areas of cooler, cloud-free air.

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Mechanisim for rain formation by cumulonimbus mammatus.

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Cumulonimbus CalvusCalvus stands for “Bald”.Calvus occurs when convection and atmospheric instability combine to push the cloud tops beyond the congestus stage to heights of up to 30,000 feet.

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The mushrooming top is a sign of the vigorous updrafts that may eventually force the cloud up into the highest levels of the troposphere. At this level of the troposphere, temperatures are normally well below freezing, and any condensation that takes place will produce ice crystals rather than water droplets. This gives the top of the cloud a brilliant, white appearance.

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REFERNCES

1. www.buzzel.com2. www.uwsp.com3. www.atmosphere.com4. www.uiuc.com5. www.climate4you.com6. www.apollo.com7. www.merrian.com8. www.anglefire.com9. www.cityofportsomuth.com10.www.mapmakermeteor.com11.www.islandnet.com12.www.jeffsweather.com13.www.mariauthorbooks.com14.www.chitambo.com

15.www.trueknowldge.com16.www.chalkrichmond.co

m17.www.mapsofworld.com18.www.airlinepilots.com

1. Meteorology Today by C. Donald Ahrens 6th edition

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