Unit 15: Environmental phenomena and related physical concepts
15.1: Modes of heat transfer
(i) Conduction is the transfer of heat energy or movement of heat through a
substance without the movement of the particles of the substance.
(ii) Convection is the transfer of heat energy in a fluid by the movement of
warmer and cooler fluid particles from place to place.
(iii) Radiation is the transfer of energy by electromagnetic waves.
Radiation does not necessarily require a material medium for the heat
energy to flow through, as is the case with convection and conduction.
15.2: Application of laws of thermodynamics in energy transfer in the
environment
The first law of thermodynamics: energy cannot be created or destroyed but
can be transformed from one form into another.
The second law of thermodynamics: energy in all forms tends to transform
itself spontaneously into a more dispersed, random, or less organized form.
This law is sometimes stated as "entropy increases"-- entropy being the
random, unavailable energy.
ACTIVITY
1. Give any three (3) everyday examples/applications of the first law of
thermodynamics.
2. Give one application of the second law of thermodynamics.
Answers
1. 3 applications of the first law of thermodynamics:
Light bulbs transform electrical energy into light energy (radiant energy).
One pool ball hits another, transferring kinetic energy and making the
second ball move.
Plants convert the energy of sunlight (radiant energy) into chemical
energy stored in organic molecules.
1
You are transforming chemical energy from your last snack into kinetic
energy as you walk, breathe, and move your finger to scroll up and down
this page.
When a hot object is placed in contact with a cold object, heat flows from
the hotter one to the colder one, never spontaneously from colder to
hotter.
2. Applications of the second law of thermodynamics
Steam engine
Heat engine
Cooler engine
15.3: Noise pollution and air pollution
I. Noise pollution is undesired sound that is disruptive or dangerous and
can cause harm to life, nature, and property.
II. Air pollution is the introduction of gases, dust particles, fumes (or smoke)
that are harmful to humans, animals and plants into the atmosphere.
III. Causes of noise pollution are: industrial and construction activities,
moving air crafts and vehicles, household appliances like radios, machines
like lawn mowers and tractors, structural damage to property like
buildings and trees due to vibrations induced by sound waves.
IV. Causes of air pollution are: forest fires, volcanic eruptions, wind erosion,
burning fossil fuels, emissions from industries, agriculture and household
chemicals, Etc.
15.4: Structure and composition of the atmosphere
The atmosphere of Earth is the layer of gases, commonly known as air
that surrounds the planet Earth and is held in place by Earth's gravity.
The air consists of a mixture of nitrogen (78%), oxygen (21%), and other
gases (1%) that surround Earth.
The atmosphere is structured into 5 layers namely: Troposphere,
Stratosphere, Mesosphere, Thermosphere and Exosphere.
2
The atmosphere through the ozone layer shields life on Earth from the
harmful ultraviolet radiation from the sun.
The gases in the atmosphere are necessary for life on earth.
15.5: Climate change science
Weather is the short-term state of the atmosphere, which may be hot or
cold, wet (rainy) or dry, calm or stormy, clear or cloudy.
Climate change refers to the large-scale changes in the long-term
averages of weather patterns.
The ozone layer is a layer in the earth’s stratosphere that absorbs most
of the ultraviolet radiation from the sun and prevent it from reaching the
earth.
The greenhouse effect occurs as follows: the sunlight reaches Earth’s
surface and is absorbed by the Earth or is reflected back into the
atmosphere. Once absorbed, the earth releases some of the energy back
into the atmosphere as heat in the form of infrared radiation.
15.6: Hydrosphere, hydrologic cycle and clouds
The hydrosphere is the combined mass of water found on, under, and
over the surface of a planet or is the liquid water component of the Earth.
The hydrological cycle is a conceptual model that describes the storage
and movement of water between the biosphere, atmosphere, lithosphere
and the hydrosphere.
3
A cloud is a visible mass of condensed water vapor floating in the
atmosphere, typically high above the general level of the ground.
Clouds are generally classified into 4 broad categories: cirrus, stratus,
cumulus, and nimbus.
15.7: Global convection currents and wind patterns
A. Cyclones and anti-cyclones
A cyclone is a large-scale, atmospheric wind-and-pressure system
characterized by low pressure at its center and by circular wind
motion, counterclockwise in the Northern Hemisphere,
clockwise in the Southern Hemisphere.
An anticyclone is a large-scale circulation of winds around a
central region of high atmospheric pressure, clockwise in the
Northern Hemisphere, counterclockwise in the Southern
Hemisphere".
B. Convection currents and global wind patterns
A convection current is the circular movement of air caused by
the cycle of warm air rising and cool air sinking. These currents
cause the global wind patterns.
15.8 Thermoregulation
Thermoregulation is the process of maintaining a body’s
constant internal core temperature despite temperature
changes in the external environment.
Thermoregulation is governed by the following Physics laws and
4
principles:
The laws of thermodynamics
The first law of thermodynamics states that, “The total amount of energy in an isolated system is
conserved.”
The second Law of thermodynamics. The law states that the spontaneous change for an irreversible
process in an isolated system always proceeds in the direction of increasing entropy.
Modes of heat transfer (conduction, convection, radiation)
Evaporation
Gibbs free energy law and
Newton’s law of cooling
Newton’s law of cooling states that the rate at which energy is lost from a
body is directly proportional to the difference between the body’s
temperature and the environmental temperature.
