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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.