Minutes of 3rd meeting (CM8001) on 22nd Mar, 2015

Minutes of 3rd meeting (CM8001) on 22nd Mar, 2015

Time: 8pm to 9pm

Venue: Online discussion

Duration: 1 hour


Xu Ziyi

Yap Keni

Yan Qucheng

Yang Xiaobin

Yap Teck Yeow

Xing Hua


1. Video Script Content

  • Chemical Concept:
  • Implications to Society:  

2. How to present the video

1st option: Hand-drawn animated characters with voice actors discussing about related topics

2nd option: Prezi video presentation with vocal explanation.

3rd option: Skit about related topics

4th option: Use of a whiteboard as canvas with vocal explanation.


Selection process : By majority of votes

Option selected: 2nd option

3. Work Distribution

  • Chemical Concept: Yap Teck Yeow, Yap Keni, Yang Xiaobin


  • Implications to Society:Xu Ziyi, Yan Qucheng, Xing Hua

Chemical Concept

Main Chemical Concepts

The Chapman Cycle

There is a cycle occurring in the stratosphere with oxygen molecules and their interaction with ultraviolet rays. This process is classified as a cycle because of the repetitive conversion between different molecules of oxygen. The ozone layer is created when ultraviolet rays react with oxygen molecules (O2) to create ozone (O3) and atomic oxygen (O). This is known as the Chapman Cycle.


Chemicals behind Chapman Cycle



  1.   An oxygen molecules is struck by UV light of higher frequency found in solar radiation (top end of UV-B, UV-C and above), creating two oxygen radicals:


  1.   Each oxygen radical then reacts with an oxygen molecule to produce an ozone molecule:



The ozone-oxygen cycle

  1.       Ozone molecules formed by the reaction above absorb radiation having wavelengths between UV-B and the very top end of UV-A. The triatomic ozone molecule becomes diatomic molecular oxygen plus a free oxygen atom :

O3 + ℎν(240-310 nm) → O2 + O

The atomic oxygen produced quickly reacts with another oxygen molecule to reform ozone:

O + O2 → O3 + K.E.

where “K.E.” denotes the excess energy of the reaction which is given off as extra kinetic energy.


These two reactions form the ozone-oxygen cycle, in which the chemical energy released when O and O2 combine is converted into kinetic energy of molecular motion. This results in a conversion of penetrating UV-B light into heat, without any net loss of ozone. This cycle maintains the ozone layer while preventing UV radiation, which is harmful to most living beings, from reaching the lower atmosphere. It is also one of two major sources of heat in the stratosphere with the other being the kinetic energy released when O2 is struck by UV light to form O atoms.



  1.   If an oxygen atom and an ozone molecule meet, they recombine to form two oxygen molecules:

O3 + O· → 2 O2

And if two oxygen atoms meet, they react to form one oxygen molecule:

2 O· → O2


This reaction is known to have a negative order of reaction of -1. The overall amount of ozone in the stratosphere is determined by a balance between production by solar radiation and removal. The removal rate is slow, since the concentration of O atoms is very low.


Certain free radicals, such as  hydroxyl (OH), nitric oxide (NO) and atoms of chlorine (Cl) and bromine (Br), act as catalysts for the recombination reaction, leading to an ozone layer thinner than it would be if the catalysts were not present.

Most of the OH and NO are naturally present in the stratosphere, but human activity, especially emissions of chlorofluorocarbons (CFCs) and halons, has greatly increased the Cl and Br concentrations, leading to ozone depletion. Each Cl or Br atom can catalyze tens of thousands of decomposition reactions before it is removed from the stratosphere.

Ozone is constantly being created and destroyed by the Chapman cycle and that these reactions are natural processes, which have been taking place for millions of years. Because of this, the thickness the ozone layer at any particular time can vary greatly. O2 is constantly being introduced into the atmosphere through photosynthesis, so the ozone layer has the capability of regenerating itself.


Chemistry of Ozone Depletion

Halocarbons are chemical compounds which contain carbon and one or more of the 5 elements known as halogens: fluorine, chlorine, bromine, iodine, and astatine. So bromine halocarbons contain carbon, bromine, and possibly other elements. Some examples of bromine halocarbons are methyl bromide, CH3Br, which is a widely used pesticide and bromofluorocarbons such as CF3Br, which are mainly used as fire extinguishers.

Bromine halocarbons are stable compounds and are not destroyed until they are transported high into the stratosphere (more than 10 kilometers above the earth). In the stratosphere, which is where the ozone layer also exists, the halocarbons are exposed to ultraviolet light from the sun, which breaks them apart and causes them to release bromine atoms. The bromine atoms then react to destroy ozone in what is known as a catalytic cycle, meaning that the bromine atoms act as a catalyst for the ozone destruction but are not themselves destroyed. Therefore, the bromine atoms can go on to destroy other ozone molecules. One example of such a catalytic cycle is the following:

Br + O3 –> BrO + O2

BrO + O –> Br + O2

At the end of this cycle, the bromine atom remains unchanged, which means it can go through the cycle again and destroy more ozone. The above cycle is not significant in ozone destruction due to bromine being present in fairly low concentrations in the atmosphere (less than 50 bromine atoms for each trillion air molecules). However, another catalytic cycle that involves bromine and chlorine (which gets into the stratosphere mainly from the release of chlorofluorocarbons is very important in destroying ozone, and largely responsible for the destruction of the global ozone layer. This cycle is:

Br + O3 –> BrO + O3

Cl + O3 –> CLO + O2

BrO + ClO –> Br + CL + O2

This cycle is more effective because it doesn’t require oxygen atoms, and because there is much more chlorine than bromine in the atmosphere. At the end of this cycle both the bromine and chlorine atoms remained unchanged and can destroy more ozone. The bromine and chlorine atoms stop destroying ozone only when they react with other chemicals to form a “reservoir” species, one that doesn’t react with ozone, such as HBr or HCl.


Polar Stratospheric clouds

As seen, the primary cause of ozone depletion is the presence of chlorine-containing source gases (primarily CFCs and related halocarbons). In the presence of UV light, these gases dissociate, releasing chlorine atoms, which then go on to catalyze ozone destruction. The Cl-catalyzed ozone depletion can take place in the gas phase, but it is dramatically enhanced in the presence of polar stratospheric clouds (PSCs).

These polar stratospheric clouds(PSC) form during winter, in the extreme cold. Polar winters are dark, consisting of 3 months without solar radiation (sunlight). The lack of sunlight leads to a decrease in temperature and the polar vortex traps and lowers the temperature of air. Temperatures hover around or below −80 °C. These low temperatures results in the formation of cloud particles. There are three types of PSC clouds—nitric acid trihydrate clouds, slowly cooling water-ice clouds, and rapid cooling water-ice clouds—provide surfaces for chemical reactions whose products will lead to ozone destruction during spring.

The key observation is that, ordinarily, most of the chlorine in the stratosphere exists in “reservoir” compounds, mainly chlorine nitrate (ClONO2) as well as stable end products such as HCl. During the Antarctic winter and spring, however, reactions on the surface of the polar stratospheric cloud particles convert these “reservoir” compounds into reactive free radicals (Cl and ClO). The process by which the clouds remove NO2 from the stratosphere by converting it to nitric acid in the PSC particles, which then are lost by sedimentation is called denitrification. This prevents newly formed ClO from being converted back into ClONO2.

The role of sunlight in ozone depletion is the reason why the Antarctic ozone depletion is greatest during spring. During winter, even though PSCs are at their most abundant, there is no light over the pole to drive chemical reactions. During the spring, however, the sun comes out, providing energy to drive photochemical reactions and melt the polar stratospheric clouds, releasing large amounts of ClO, which drives the hole mechanism. Further warming temperatures near the end of spring break up the vortex around mid-December. As warm, ozone and NO2-rich air flows in from lower latitudes, the PSCs are destroyed, the enhanced ozone depletion process stops, and the ozone hole closes.

Most of the ozone that is destroyed is in the lower stratosphere, as compared to the much smaller ozone depletion through homogeneous gas phase reactions, which occurs primarily in the upper stratosphere.



Depletion of Ozone Layer. Retrieved from


 Ozone-oxygen cycle. Retrieved from


Chemicals in the atmosphere. Retrieved from


 Ozone layer depletion: effects and causes of ozone depletion. Retrieved from


 How do bromine halocarbons effect the ozone layer?. Retrieved from




Implications to society

Effects on human health

The ozone depletion has significant effects on human health in terms of skin cancers, cataracts and immune system.

Skin Cancers

The evidence for UV becoming a vital factor in skin cancers are as follows. First of all, there is an increase in UV-B intensity with the decrease in latitude. Furthermore, skin cancers happen most likely in those areas with high UV exposures. And it happens more often on people who have frequent outdoor operations. Moreover, it’s higher for men than women. With an increase in age, the probability gets higher also.

Throughout the world, there are mainly two types of skin cancers, which are melanoma and non-melanoma. Melanoma is typically a severe form of skin cancer and it’s increasing at an enormous rate. Non-melanoma is the most common form of cancers. However, there is no sufficient evidence to prove the inside relationship between melanoma skin cancer and increasing UV exposures. (IARC,1994)  Based on a study conducted in Norway in four different latitudes (Henrikson, et al., 1988, 1990) , the biological amplification factor for non-melanoma skin cancer was shown to be around 2.0.


Apart from higher chances of skin cancer, high intensity of UV light results in causing cataracts, which is a major factor of blindness in the world with over half of the blindness incidences are caused by cataracts (UNEP, 1994). Unlike the mechanism of skin cancer, cataracts are mainly caused by UV-A. Nevertheless, a study (Taylor & McCarty, 1996) suggests that UV-B also causes cataracts.

When the sunlight strike on the normal eye, the light hits cornea first followed by lens, vitreous humor and lastly retina. A various studies show that a large amount of UVR never reach retina, they are absorbed by lens and cornea. The cornea absorb the light with the wavelength below 300nm (mostly UV-B), and the lens absorb the radiation with the wavelength below 370nm (mostly UV-A). That’s also why the artificial replacement lenses involve UV absorption segments.

Immune System

Excessive exposure of UVR may affect the functionality of immune system. As far as a human body concerns, the skin is the first barrier which protect us from the outside virus and bacteria that may carry infect agents. In order to protect our body, the immune system needs to identify the cells that do not function optimally and clear them if necessary. However, after extensive contact with UVR, the skin cells may be degenerated and lose its functionality. As a result, the skin is no longer able to defense and immune system is partially damaged.

Effects on agriculture

In this day and age, there are arguably parallel possibilities for UVR to be experimented in the enhancement of crop production, nevertheless controversy debates have been carried out focusing on the results for plant productivity due to the threat of increased UV-B levels. Ozone depletion which radiates more UV-B will require the use of UV-B tolerant cultivars and the development of new types of crop. Much evidence suggests that there will be a side effect on crops, but these effects are relatively hard to estimated quantitatively (UNEP, 1994; Tevini, 1993).

Effect on Ecosystem


Terrestrial Ecosystem


Terrestrial ecosystems: the largest store of active organic carbon in the biosphere, including biomes of widely variable climate regimes with a diverse set of organisms adapted to this range of conditions.


Anthropogenic activity can directly and indirectly affect terrestrial ecosystem. Superimposed on temperature, atmospheric CO2, and altered precipitation patterns are changes in the levels of solar UV-B radiation, which can cause stratospheric ozone depletion and other atmospheric factors. Since 1979, a significant increase in UV-B radiation reaching the Earth’s surface has been calculated through incorporate satellite measurements of ozone, cloud and aerosol reflectivity. All latitudes except the equatorial zone have shown this increase and the largest increments takes place at mid to high latitudes in the Southern Hemisphere.

Relations of human activities with the environmental problems such as ozone depletion and climate change. The most severe damage of ozone layer happens in southern hemisphere.


The enhanced UV-B radiation results in ~3-4% negative effect on plant growth. Also, a comprehensive meta-analysis of UV-B supplementation studies showed that the average response to treatments that simulated 10 to 20% depletion of ozone was a 6% reduction in plant biomass. Another more recent meta-analysis suggested that woody perennials are more sensitive to UV-B radiation than herbaceous plants in average.

Relations between UV-B radiation amount change with the growth condition of plants.


Although terrestrial ecosystems at high latitudes are not highly productive for grazing, timber production, etc., the influence of ozone reduction on these systems may be important. The Swedish subarctic and southern Argentinean systems, for example, are not only suffering ozone depletion, but also under greatest global warming because carbon sequestration is generally quite high in these ecosystems, including the extensive peat formations. Thus, they are exposed to several features of climate change. In the Northern Hemisphere, these high latitude ecosystems are also very important for the survival of indigenous ethnic groups.

Data has shown that ozone depletion may trigger/contribute to other environmental problem such as climate change. So ozone depletion will affect terrestrial ecosystem regardless location or latitude.


Aquatic/Marine Ecosystem


Although there are many uncertainties, increased UV-B radiation has a very real potential for significant impacts on aquatic ecosystems, especially on phytoplankton and larvae of higher organisms.


Marine phytoplankton is fundamental in the food chain and the oceanic carbon cycle, for it can convert atmospheric carbon dioxide into oxygen through photosynthesis. The phytoplankton organisms are the bases of the marine food chain. They are concentrated in high latitudes where stratospheric ozone depletion is predicted to cause the greatest increase in the amount of UV-B radiation reaching the Earth’s surface. Circumpolar region contain densities of phytoplankton approximately 10 to 100 times larger than equatorial regions (UNEP, 1994). Upwelling areas along the continental shelves are other concentrating areas for phytoplankton. Investigations in Antarctica indicate that phytoplankton productivity has already been affected by current UV-B radiation levels (UNEP, 1994; Tevini, 1993).

Food chain supply and energy flow mechanism for aquatic ecosystem. UV-B radiation will start to speed up the growth of plankton(question: here is different from my research). impact on plankton growth will have influence in the aquatic ecosystem in the long run.


Early developmental stages of fish, shrimp, crab, amphibians, and other animals are also limited by current UV-B radiation levels (UNEP, 1994). As for zooplankton, they could be significantly impacted by the UV-B radiation caused by a 16% ozone reduction. The predicted increase in daily UV-B irradiance within the upper 1 to 2m would exceed the daily dose found to cause a significant reduction on survival of most zooplankton species.

UV-B radiation also have negative impact on marine animals.


Effect on biogeochemical cycles and materials

The implication of ozone depletion on terrestrial and marine ecosystem is just a glance of how ozone depletion is actually influence the biogeochemical cycles. With the change from ecosystem and UV-radiation, the global climate would thus change as a response. Right now we are not sure how much and the direction it will change the climates, but one thing is sure. It has been suggested that the imbalance of the biogeochemical cycle would enhance the greenhouse effects.


When we shift our attention out of the ecosystem, we discover that the ozone depletion is in fact affect all aspect of the earth. It may starts from the daily materials we used. The excessive UV-B radiation from ozone depletion have effects on everything such as the physical and chemical properties of materials, such as weaken the elastic properties and shorten the operation life of plastic and rubber.



Jenkins, R. (1998) . A Summary of the Biological & Human Health Risks of Stratospheric Ozone Depletion. Retrieved from http://www.ozonedepletion.info/health_report/ozone.html


deMenocal, P. (2002) . Human Health and Ecological Consequences of Ozone Depletion. Retrieved from http://eesc.columbia.edu/courses/v1003/lectures/ozone_health/


Wargent, J.J. , & Jordan, B.R. (2013). From ozone depletion to agriculture: understanding the role of UV radiation in sustainable crop production. Retrieved from http://www.ncbi.nlm.nih.gov/pubmed/23363481

Effects of Ozone Depletion on eyes and immune system. Retrieved from https://www.e-education.psu.edu/egee102/node/2026


Health and Environmental Effects of Ozone Layer Depletion. Retrieved from http://www.epa.gov/spdpublc/science/effects/index.html

C.L.Ballare, M.M.Caldwell, S.D.Fllint, S.A.Robinson, & J.F.Bornman (2010). Effects of solar ultraviolet radiation on terrestrial ecosystems. The Environmental Effects Assessment Panel Report for 2010, P105.

John Hardy, & Hermann Gucinski (1989). Stratospheric Ozone Depletion: Implications for Marine Ecosystem. Oceanography, November, 1989.

Impact of Ozone Depletion. Retrieved from: http://www.ozonedepletion.info/education/part2/ozoneimpact.html

Implications for Agricultural, Forest and other Ecosystems. Retrieved from: http://sedac.ciesin.columbia.edu/ozone/docs/UNEP98/UNEP98p29.html

Ozone Depletion & Aquatic Life. Retrieved from: http://www.ozone-hole.org.uk/14.php

  STRATOSPHERIC OZONE DEPLETION: IMPLICATIONS FOR MARINE ECOSYSTEMS. Retrieved from: http://www.tos.org/oceanography/archive/2-2_hardy.pdf




1.Problem: The individual quiz is too long and content is too heavy. Sometimes, we may just focus on rushing through the questions rather than understanding the concepts and explanation deep inside.

Solution: Maybe shorten the number of questions in the quiz, and focus more on the explanation. What about providing the hint or explanations after the group quiz in another ppt? Because even if we get the answer right, sometimes we don’t really understand the reason. The extra explanations help to reinforce the point that Prof wanted to emphasis also.

2. Problem: It is not clear about the importance of content in each unit. We don’t really know within each unit which are the concept or materials more important and which are the things for information or interest only?

Solution: Providing a list consisting the most important concept in each unit, so before the quiz we know where shall we pay more attention.

3. Problem: We don’t know what format of blog are you expected.

Solution: Maybe every 2 two week, you can select 2 or 3 blogs that you think can represent the standard you want us to reach.

About the team

The Hangover!!!



Our group consists of people who came from different background and field. We believe that we have been assigned into the same group as we all have the same passion in science, we concern about the environmental issues occurring currently and the impact of chemistry on society. We hope that we can really enjoy this course, enjoy what chemistry bring to us and “hangover” together!”

Team member

Name: Xing Huaxing hua

School: School of Electrical and Electronic Engineering

Course: Electrical and Electronic Engineering

Year: 2

Why taking this course:  Everything is made of chemicals, so as the human and all the stuff we can see in daily life. Many of the changes that we may observe are also caused by chemical reactions. Knowing some chemistry helps us to make decisions and troubleshoot problems in a more reasonable way.qucheng

 Name: Yan Qucheng

School: School of Mechanical and Aerospace Engineering

Course: Mechanical Engineering

Year: 2

Why taking this course: Want to figure out how chemistry change our life.

teck yeowName: Yeo Teck Yeow

School: Renaissance Engineering/ Year 1

Course: Renaissance Engineering

Year: 1

Why taking this course: Chemistry has always been a favorite subject and it would be interesting to look at it outside of usual academic content.

Name: Yangxiaobin Xiao Bin

School: School of Mechanical and Aerospace Engineering

Course: Mechanical Engineering with business minor

Year: 1

Why taking this course :Passion in chemistry and concern about the impact of chemistry on our society and raise awareness on environmental issue.

Name: Yap Kkenieni

School: School of Biological Sciences

Course: Biological Sciences

Year: 1

Why taking this course: It is always fun to learn how different fields of sciences are correlated and their impact on society. Besides, I believe that the team based learning carried out in this course is going to benefit me and my team members in many ways.

Name: Xziyiu Ziyi

School: School of Civil and Environmental engineering

Course: Maritime Studies with a second major in Business

Year: 1

Why taking this course: Interest to chemistry & concern to the society. This course is related to my another course which is also about the environment. I hope that I can apply what I’ve learned to the reality, not just some theories.


What Is The Ozone Layer?

The ozone layer refers to a region of Earth’s stratosphere which absorbs most of the Sun’s UV radiation. It contains high concentrations of ozone (O3) as compared to the other levels of the atmosphere, however, the concentration is still relatively small compared to other gases in the stratosphere. The ozone layer contains fewer than ten parts per million of ozone, whereas the average ozone concentration in Earth’s atmosphere as a whole is only about 0.3 parts per million. The ozone layer is mainly found in the lower portion of the stratosphere, approximately 20 to 30 kilometres above the earth surface. Factors such as the season and geographical location affects the thickness of the ozone layer.

The ozone layer absorbs 97–99% of the Sun‘s medium-frequency ultraviolet light which has a wavelength of about 200 nm to 315 nm, stopping potential damage to exposed life forms near the surface.

Chemical Process

Ozone in the Earth’s stratosphere is created through two processes. Firstly, when ultraviolet light strikes oxygen molecules containing two oxygen atoms (O2), it splits them into individual oxygen atoms (atomic oxygen)

O2 + ℎνuv → 2O

The atomic oxygen then combines with unbroken O2 to create ozone, O3. However, the  ozone created is chemically unstable and when ultraviolet lights strikes it, it splits into a molecule of O2 and an atom of atomic oxygen. This results in a continuing process known as the ozone-oxygen cycle.

O + O2 ↔ O3

Ozone Depletion

There are many various causes of ozone depletion.

But the largest cause would due to the reaction of ozone with free radicals such as nitric oxide (NO), nitrous oxide (N2O), hydroxyl (OH), chlorine (Cl), and bromine (Br). While most of them can be found naturally, the concentrations of chlorine, and bromine have increased significantly in recent years due to the release of large quantities of man-made organohalogen compounds, especially chlorofluorocarbons (CFCs) and bromofluorocarbons. These highly stable compounds are capable of surviving the rise to the stratosphere, where the radicals are liberated by the action of ultraviolet light. Each radical is then free to initiate and catalyze a chain reaction capable of breaking down over 100,000 ozone molecules. This results in a reduced capability of the ozone layer to absorb the ultraviolet radiation.


Other causes of ozone depletion can be natural such as large volcanic eruptions which can have an indirect effect on ozone levels. When volcanoes erupt, they produce massive clouds of ashes into the troposphere, and then they drift upward into the stratosphere. These ashes contain high concentration of bromine and chlorine. Ashes can stay in the stratosphere for about two to five years, and causing chemical reactions that can damage the ozone layer withn this period of time.

Effect of Ozone Depletion

Ozone depletion results in the amount of UV light reaching the earth surface to increase which has a varied impact on the various living things on earth. For example, in the case of humans, this leads to a rise in getting skin cancer and possibly cataracts — a clouding of the eye’s lens. As for plants, UV light results in various changes in the growth mechanisms of the plant, some possibly more beneficial than damaging. Other affected parties include the marine ecosystem, biogeochemical cycles, materials and et cetera.

Minutes of 2nd meeting (CM8001) on 5th March, 2015

Minutes of 2nd meeting (CM8001) on 5th March, 2015


Time: 10am to 11am

Venue:  Online Discussion

Duration: 1 hour



Xu Ziyi

Yap Keni

Yan Qucheng

Yang Xiaobin

Yap Teck Yeow

Xing Hua



1. Chemical concept

• The Chapman Cycle
• the causes of depletion of the ozone layer and the chemical concepts behind it

2. Implications to society

• Humans – business, health, agriculture
• Ecosystem – animal, plants
• Biogeochemical
• Materials
• Any other thing you can find(Animals, global warming(ice caps), etc)

3. Work Distribution:

• chemical concept: Yap Teck Yeow, Yap Keni, Yang Xiaobin
• chemical implication : Xu Ziyi, Yan Qucheng, Xing Hua



Minutes of 1st meeting (CM8001) on 10th Feb, 2015

Minutes of 1st meeting (CM8001) on 10th Feb, 2015

Time: 12pm to 1pm

Venue: N2.1 Starbucks

Duration: 1hour


Xu Ziyi

Yap Keni

Yan Qucheng

Yang Xiaobin

Yap Teck Yeow

Xing Hua


  1.   Project Introduction:
  •       Discuss the importance of the topic we choose.
  1.   About the team.
  •       Discuss the team spirit.
  •       Team Information
  1.   Future Plan for the project
  •       Next meeting
  1.   Work Distribution:
  •       Project Introduciton: Yap Teck Yeow, Yang Xiaobin, Yan Qucheng
  •       About the team: Xu Ziyi, Yap Keni, Xing Hua


Team question session 3

Q1. Understanding Earth’s energy balance is essential to understanding the issue of global    warming. For example, the solar energy striking Earth’s surface averages 168 watts per square meter (W/m2), but the energy leaving Earth’s surface averages 390 W/m2. Why isn’t Earth cooling rapidly?


Ans: The atmosphere retains much of the energy emitted from the surface. This is known as the greenhouse effect.


Q2. Do you think the statement made by the cartoon is justified? Explain.

      “ This winter has lowered my concerns about global warming.”


Ans: Firstly, global warming is a global issue, we should not only concern about the weather           of a certain region. Even if we focus on a certain region, the duration of winter or the      temperature might also be different, which are so-called symptoms of the global warming.

Secondly, global warming is a long-term issue, we cannot identify the difference in a short period of time comparing in terms of decades or centuries.


Q3. One of the first radar devices developed during World War Two used microwave radiation of a specific wave range that triggers the rotation of water molecules. Why was the design not successful?


Ans: While using radar in rainy days or in the sea war, where has a high concentration of water vapor, the microwave would contribute to the rotation of water molecules instead of conveying information. The energy of microwave is transformed into energy of water molecules (possibly heat). So the design is unsuccessful.


Q4. Now that you have studied air quality (Unit 1), stratospheric ozone depletion (Unit 2), and global warming (Unit 3), which do you believe poses the most serious problem for you in the short run? In the long run?


Ans: Short run-air quality: It relates the most to our daily life because we breathe everyday. All the smoke, soot, dust and etc will definitely affect directly to our health.

Long run-global warming: As the temperature keeps rising up, the Earth would not be suitable for living any more. And high temperature causes the sea levels to rise, as a result, some parts of land which may has large populations will submerge under water.