BS 3rd Sem (E) Report on Temperature, Pressure, and Global Circulation

This report, submitted by Muhammad Maaz from GC University Faisalabad, delves into the concepts of temperature, pressure, and global circulation. It defines temperature as a measure of hotness or coldness and discusses its scales (Celsius, Fahrenheit, Kelvin) and its impact on various physical processes. The report then defines pressure, explaining gauge pressure and various units of measurement, and explores its effects, including hydrostatic and atmospheric pressure. Finally, it details global circulation patterns, including the Hadley, Ferrel, and Polar cells, and explains the Coriolis effect and its influence on wind patterns and weather systems, including the jet stream. The report concludes by referencing sources such as Wikipedia and Britannica to support its findings. This assignment is available on Desklib, a platform providing AI-based study tools for students.

GC University Faisalabad
(Department of English literature)
Submitted by
Muhammad Maaz
Roll no
1936
Class
BS 3rd Semester (E)
Session
2020_2024
Group #
II
Submitted to
Mam Ayesha Riaz

Temperature, Pressure And Global Circulation
Temperature:
Temperature is a physical quantity that expresses hot and cold. It is the manifestation of t
energy, present in all matter, which is the source of the occurrence of heat, a flow
when a body is in contact with another that is colder or hotter. Temperature is important i
fields of natural science, including physics, Chemistry,Earth science, astronomy,
medicine, biology, ecology, materialscience, metallurgy,mechanicalengineeringand
geography, as well as most aspects of daily life.
Effects
Many physical processes are related to temperature, some of them are given below:

 the physicalpropertiesof materialsincludingthe phase(solid, liquid, gaseousor
plasma), density, solubility, vapourpressure, conductivity, hardness, wearresistance, thermal
conductivity, corrosion resistance, strength.
 the rate and extent to which chemical reactions occur.
 the amount and properties of thermal radiation emitted from the surface of an object.
 air temperature affects all living organisms.
 the speed of sound which is a function of the square root of the absolute temperature.
Scales
The Celsius scale (°C) is used for common temperature measurements in most of the worl
an empiricalscale that was developedby historicalprogress,which led to its zero
point 0 °C being defined by the freezing point of water, and additional degrees defi
that 100 °C was the boiling point of water, both at sea-level atmospheric pressure. Becaus
100-degree interval, it was called a centigrade scale. Since the standardization of the kelv
the International System of Units, it has subsequently been redefined in terms of the equiv
fixing points on the Kelvin scale, and so that a temperature increment of one degree Celsi
the same as an increment of one kelvin, though they differ by an additive offset
273.15.
The United States commonly uses the Fahrenheit scale, on which water freezes at 32 °F a
at 212 °F at sea-level atmospheric pressure.
At the absolute zero of temperature, no energy can be removed from matter as he
expressedin the thirdlaw of thermodynamics.At this temperature,mattercontainsno
macroscopic thermal energy, but still has quantum-mechanical zero-point energy as predi
the uncertainty principle, although this does not enter into the definition of absolute temp
Experimentally, absolute zero can be approached only very closely; it can never be reache
temperatureattainedby experimentis 100 pK).Theoretically,in a body at absolutezero
temperature, all classical motion of its particles has ceased and they are at complete rest
classical sense. The absolute zero, defined as 0 K, is exactly equal to −273.15 °C, or −459
Many scientific measurements use the Kelvin temperature scale (unit symbol: K), n
honor of the . It is an scale. Its numerical zero point, 0 K, is at the of temperature. Since M
2019, its degrees have been defined , and statistical mechanics. In the (SI), the magnitud
kelvin is defined through various empirical measurements of the average kinetic en
microscopic particles. It is numerically evaluated in terms of the , the value of which is defi
as fixed by international convention.

Pressure: Pressureisthe force appliedperpendicularto the surfaceof an object per
unit area over which that force is distributed. Gauge pressure (also spelled gage pressu
pressure relative to the ambient pressure.
Various units are used to express pressure. Some of these derive from a unit of force divid
unit of area; the SI unit of pressure, the pascal (Pa), for example, is one newton per

metre (N/m2); similarly, the pound-force per square inch (psi) is the traditional unit of pressu
the imperial and U.S. customary systems. Pressure may also be expressed in terms
atmospheric pressure; the atmosphere (atm) is equal to this pressure, and the torr is
as1 760 of this. Manometric units such as the centimetre of water, millimetre of mercury, and
of mercury are used to express pressures in terms of the height of column of a particular fl
a manometer.
Measurement, Types and Effects of Pressure
The pressure exerted by a confined gas results from the average effect of the forces produ
the containerwalls by the rapid and continualbombardmentof the huge numberof
gas molecules. Absolute pressure of a gas or liquid is the total pressure it exerts, including
effect of atmospheric pressure. An absolute pressure of zero corresponds to empty
complete vacuum.
Measurement of pressures by ordinary gauges on Earth, such as a tire-pressure gauge, ex
pressure in excess of atmospheric. Thus, a tire gauge may indicate a pressure of 30 pound
square inch), the gauge pressure. The absolute pressure exerted by the air within t
including atmospheric pressure, is 45 pounds per square inch. Pressures less than atmosp
are negative gauge pressures that correspond to partial vacuums.
Hydrostatic pressure is the stress, or pressure, exerted equally in all directions at points w
confined fluid (liquid or gas). It is the only stress possible in a fluid at rest. See P
principle.

Biostatic pressure, the stress exerted on a body of rock by surrounding rock, is a p
Earth’s crust somewhat analogous to hydrostatic pressure in fluids. Lithostatic pressure in
with depth below Earth’s surface.
Atmospheric Pressure
Atmospheric pressure, also known as barometric pressure (after the barometer), is the pre
within the atmosphere of Earth. Air pressure is caused by the weight of the air molecules a
Even tiny air molecules have some weight, and the huge numbers of air molecules that m
the layers of our atmosphere collectively have a great deal of weight, which presses do
whatever is below.
Global Circulation
The global circulation can be described as the world-wide system of winds by whic
necessary transport of heat from tropical to polar latitudes is accomplished. In each hemis
there are three cells (Hadley cell, Ferrel cell and Polar cell) in which air circulates through
entire depth of the troposphere.

Hadley cell
The largest cells extend from the equator to between 30 and 40 degrees north and south,
named Hadley cells, after English meteorologist George Hadley.
Within the Hadley cells, the trade winds blow towards the equator, then ascend near the e
as a broken line of thunderstorms, which forms the Inter-Tropical-Convergence Zone
From the tops of these storms, the air flows towards higher latitudes, where it sinks to pro

high-pressure regions over the subtropical oceans and the world's hot deserts, such as the
desert in North Africa.
Ferrel cell
In the middle cells, which are known as the Ferrel cells, air converges at low altitudes to a
along the boundaries between cool polar air and the warm subtropical air that generally o
between 60 and 70 degrees north and south. This often occurs around the latitude
which gives us our unsettled weather. The circulation within the Ferrel cell is complicated
return flow of air at high altitudes towards the tropics, where it joins sinking air from the H
cell.
The Ferrel cell moves in the opposite direction to the two other cells (Hadley cell and Pola
and acts rather like a gear. In this cell the surface wind would flow from a southerly direct
the northern hemisphere. However, the spin of the Earth induces an apparent motion to th
in the northern hemisphere and left in the southern hemisphere. This deflection is caused
Coriolis effect and leads to the prevailing westerly and south-westerly winds often experie
over the UK.
Polar cell
The smallest and weakest cells are the Polar cells, which extend from between 60 and 70
north and south, to the poles. Air in these cells sinks over the highest latitudes an
towards the lower latitudes at the surface.
The Coriolis effect, winds and UK weather
Now we know about the Hadley, Ferrel and Polar cells, let’s take a look at how all that tran
to what we see at the Earth’s surface. As a result of the Earth’s spin, each cell has prevaili
winds associated with it, and we also have jet streams, all influenced by something called
Coriolis effect. This explains why air moves in a certain direction around an area
pressure, and why trade winds exist. It also gives us an idea of why we see certain weathe
around the UK.
Warm moist air from the tropics gets fed north by the surface winds of the Ferrel cell. This
meets cool dry air moving south in the Polar cell. The polar front forms where th
contrasting air mass meet, leading to ascending air and low pressure at the surface, often
the latitude of the UK.
The polar front jet stream drives this area of unstable atmosphere. The UK and m
countries in Europe often experience unsettled weather, which comes from travelling
low pressure which form when moist air rises along the polar front.

Weather (or low pressure) systems bearing rain and unsettled conditions move acr
Atlantic on a regular basis. The jet stream guides these systems, so its position is importa
UK weather.
Normally the jet stream runs fairly directly from west to east and pushes weather
through quite quickly. However, sometimes the steering flow of the jet stream can meand
like a river), curving north and south as it heads east across the Atlantic. This is
meridional flow, with the more linear west to east flow being called a zonal flow.
During a meridional flow areas of low pressure can become stuck over the UK lea
prolonged periods of rain and strong winds. During the winter the polar front jet stream m
further south leading to a greater risk of unsettled weather, and even snow if cold
masses move south over the UK.
The continued effect of the three circulation cells (Hadley cell, Ferrel cell and Pola
combined with the influence of the Coriolis effect results in the global circulation. The net
is to transfer energy from the tropics towards the poles in a gigantic conveyor belt.
References https://en.m.wikipedia.org/wiki/Temperature https://en.m.wikipedia.org/wiki/Pressure#:~:text=Pressure%20(symbol%3A%20p%20o
P,which%20that%20force%20is%20distributed.&text=Pressure%20may%20also%20be
expressed,1%E2%81%84760%20of%20this. https://www.britannica.com/science/pressure https://www.metoffice.gov.uk/weather/learn-about/weather/atmosphere/global-circulati
patterns#:~:text=The%20global%20circulation%20can%20be,entire%20depth%20of%
%20troposphere.