SS20702 METEOROLOGY AND CLIMATE CHANGES

TITLE : THE CLOUD AND ITS CLASSIFICATION

LECTURER’S NAME : DR JUSTIN

DATE OF SUBMISSION : 17th DECEMBER 2015

NAME MATRIC NUMBER

SITI NORHUDA BINTI ABDULLAH BS14110112

1.0 INTRODUCTION

By people sight, cloud might be the best scenery ever, where it creates calm and

beautiful sky. Most of the time, it appears with white appearance or else in blue color,

but sometimes, it would be grey in color which bring to a rainy condition. Cloud affects

our daily weather and play key roles in the global climate. Through their ability to

precipitate, clouds provide virtually all of the fresh water on the Earth and are a crucial

link in a hydrologic cycle (Dennis & Johannes, 2011).

The condensation of water which formed from water droplets and ice particles

suspended in atmosphere so called as aerosol will then become cloud. The water vapor

is so persuasive in our daily life that many do not know that is concentration is actually

quite small (Wang, 2013). In clouds, the liquid droplets formed by condensation are

small and light enough that they stay in the air. If they grow large enough, they will fall

to the ground as precipitation.

Clouds form when the air is saturated and cannot hold any more water vapor. It

is happened when the amount of water in the air has increased, for example through

evaporation which went to the point that the air cannot hold any more water. Besides,

cloud also formed when the air is cooled to its dew point, the point where condensation

occurs and when the air is unable to hold any more water. In fact, the warmer the air is,

the more water vapor that it can hold. Through condensation, as the air rises, it will cool

and reducing the temperature of the air decreases its ability to hold water vapor so that

condensation occurs. The height at which dew point is reached and clouds form is called

the condensation level.

The air is normally cooled by expansion during its upward movement. Upward

flow of air in the atmosphere may be caused by convection resulting from intense solar

heating of the ground; by a cold wedge of air (cold front) near the ground causing a

mass of warm air to be forced aloft; or by a mountain range at an angle to the wind.

Clouds are occasionally produced by a reduction of pressure aloft or by the mixing of

warmer and cooler air currents.

Figure 1 : Temperature profile of a parcel of air as rises through the atmosphere

To understand easier, there are five factors causing the cloud formations, which

are surface heating, topography or orography forcing, frontal, convergence and

turbulence. Surface heating happens when the ground is heated by the sun which heats

the air in contact with it causing it to rise. The rising columns are often called thermals.

Surface heating tends to produce cumulus clouds (we will see how does the cumulus

cloud look alike on the results). Next, topography or orographic forcing or shape and

features of the area can cause clouds to be formed. When air is forced to rise over a

barrier of mountains or hills it cools as it rises. Layered clouds are often produced this

way.

Figure 2 : Cloud caused by surface heating

Figure 3 : Clouds caused by topography

Frontal is where clouds are formed when a mass of warm air rises up over a

mass of cold, dense air over large areas along fronts. A 'front' is the boundary between

warm, moist air and cooler, drier air. While convergence is the streams of air flowing

from different directions are forced to rise where they flow together, or converge. This

can cause cumulus cloud and showery conditions. The turbulence is a sudden change in

wind speed with height creating turbulent eddies in the air.

Figure 4 : Clouds caused by convergence

2.0 TYPES OF CLOUDS

In 1801, French naturalist Jean Lamarck had made the classification of cloud. Later in

1803, Luke Howard, an English scientist, devised a classification that was adopted by

the International Meteorological Commission in 1929, designating three primary cloud

types, cirrus, cumulus, and stratus, and their compound forms, which are still used

today in modified form. Till now, today's classification of clouds has three main divisions,

which are high clouds, 20,000 to 40,000 ft (6,100–12,200 m), intermediate clouds,

6,500 to 20,000 ft (1,980–6,100 m) and middle low clouds, near ground level to 6,500 ft

(1,980 m). There are also clouds with vertical development, which are 1,600 ft to over

20,000 ft (490–6,100 m). Clouds form in three basic patterns, which are:

i. Cirrus, from cirro, meaning curly or fibrous

ii. Stratus, from strato, suggesting sheets or layers

iii. Cumulus, from cumulo, indicating heaped or piled

By combining other terms, a number of different cloud combinations can be described.

The Latin word for shower is nimbus. So the technical term for describing the cloud

associated with thunderstorms is cumulonimbus. Adding to the list of Latin suffixes and

prefixes, we encounter terms like fracto (referring to broken or fractured) and

lenticularis (lens-shaped).

Table 1 : The height of clouds

2.1 HIGH CLOUD

High cloud forms include cirrus, detached clouds of delicate and fibrous appearance,

generally white in color, often resembling tufts or featherlike plumes, and composed

entirely of ice crystals; cirrocumulus (mackerel sky), composed of small white flakes or

very small globular masses, arranged in groups, lines, or ripples; and cirrostratus, a thin

whitish veil, sometimes giving the entire sky a milky appearance, which does not blur

the outline of the sun or moon but frequently produces a halo.

Figure 5 : Cirrus uncinus (Ci unc)

Figure 6 : Cirrostratus (Cs)

Figure 7 : Cirrostratus nebulosus

Figure 8 : Cirrocumulus stratiformis (Cc str)

Figure 9 : Cirrocumulus floccus (Cc flo)

2.2 INTERMEDIATE CLOUD

Intermediate clouds or middle clouds include altocumulus, patchy layer of flattened

globular masses arranged in groups, lines, or waves, with individual clouds sometimes

so close together that their edges join; and altostratus, resembling thick cirrostratus

without halo phenomena, like a gray veil, through which the sun or the moon shows

vaguely or is sometimes completely hidden.

Figure 10 : Altocumulus lenticularis (Ac len)

Figure 11 : Altocumulus castellanus (Ac cas)

Figure 12 : Altocumulus stratiformis (Ac str)

Figure 13 : Altostratus opacus (As op)

2.3 LOW CLOUDS

Low clouds include stratocumulus, a cloud layer or patches composed of fairly large

globular masses or flakes, soft and gray with darker parts, arranged in groups, lines, or

rolls, often with the rolls so close together that their edges join; stratus, a uniform layer

resembling fog but not resting on the ground; and nimbostratus, a nearly uniform, dark

grey layer, amorphous in character and usually producing continuous rain or snow.

Figure 14 : Cumulonimbus capillatus (Cb cap)

Figure 15 : Stratocumulus stratiformis (Sc str)

Figure 16 : Stratocumulus castellanus (Sc cas)

Figure 17 : Cumulus mediocris (Cu med)

Figure 18 : Cumulus humilis (Cu hum)

Figure 19 : Stratocumulus (Str)

2.4 VERTICAL DEVELOPMENTS

Clouds having vertical development include cumulus, a thick, detached cloud, generally

associated with fair weather, usually with a horizontal base and a dome-shaped upper

surface that frequently resembles a head of cauliflower and shows strong contrasts of

light and shadow when the sun illuminates it from the side, and cumulonimbus, the

thunderstorm cloud, heavy masses of great vertical development whose summits rise in

the form of mountains or towers, the upper parts having a fibrous texture, often

spreading out in the shape of an anvil, and sometimes reaching the stratosphere.

Cumulonimbus generally produces showers of rain, snow, hailstorms, or thunderstorms

Low clouds are clouds at low altitude, usually below 2,000 meters. There are three types

of low clouds, all called 'stratus.' You now know this means they cover the entire sky,

but this time, much closer to the surface of the Earth. Stratus clouds are what you see

on a dreary, hazy day.

Stratocumulus are also low and gray, but since they have the word 'cumulus' in them,

this means that they have a bit more shape to them. These are lumpy layers across the

sky, though they rarely produce rain. Nimbostratus clouds are the ones that make you

want to just stay inside all day. They are dark and wet looking, and often produce a

decent amount of rain.

Finally, we have vertical clouds, which are clouds that form vertically instead of

horizontally. There are two types of vertical clouds, cumulus and cumulonimbus. Since

they both have the word 'cumulus' in them, we know that they are both big, fluffy

clouds. Cumulus clouds are the ones we can see shapes in when we look up at them in

the sky.

3.0 CONCLUSION

Based on this observation study to the cloud in the sky during the day, we found a

variety shape of cloud. We take a few photo and name it based on different term and

shape it forming. The common type of cloud was cirrus, stratus and cumulus. The hibrid

name mean the combination between two basic type of cloud, for example, the stratus

combine with cirrus to form a cirrostratus. This combination happen because of the

different altitude and pressure happen on that particular area. The atmospheric activities

among the cloud define the weather carried by it and always change based on time and

wind speed. The formation and development of cloud also depend on how high the air

masses can rise up during the convection and uplifting process

4.0 REFERENCES

C. Tina.Cloud Identification Guide. Marshall University.

Dennis L., Johannes V., 2011, Physics and Chemistry of Clouds, Cambridge University

Press, New York.

Donald Ahrens ,2012 , Essentials of Meteorology An Invitation to The Atmosphere,

Seventh Edition, Cengage Learning, United States of America.

Donald Ahrens, 2003, Meteorology Today An Introduction to Weather, Climate, and the

Environment, Seventh Edition, Thomson Learning, United States of America.

Moran Morgan ,1994, Meteorology The Atmospere and The Science of Weather, Fifth

Edition, Prentice Hall.

Pao K. W., 2013, Physics and Dynamics of Clouds and Precipitation, Cambridge

University Press, New York.