Disasters - LMHS Science Classroom...

Senior ScienceSenior Science HSCHSC CourseCourse Disasters - 1 -

Disasters – identify disasters as events associated with large-scale environmental or

structural damage and/or loss of life – identify a range of natural disasters, with the aid of specific Australian

examples – identify a range of disasters associated with human activity using specific

Australian examples – identify specific Australian examples where nature and human activity have combined to produce disasters

such as dust storms, shipwrecks, landslides and accidents

Natural Disasters We all know that life is not totally safe. What is a disaster? Write a suitable definition

There are many hazards that could cause us harm, list examples of disasters that have or may effect you:

Which ones can/should we prepare for? Which have occurred and will occur again in Australia?

Classifying disasters Disasters can be natural events or can be caused by people. There are other ways to classify disasters but to make it simple we will leave it this way that the disaster is either a natural event or caused by people. Classify the disasters mentioned as either natural or caused by people. List them in the table.

Natural events Caused by people


Did you notice that there are some disasters listed in both categories? This is sometimes the case. For example, fires may be caused by lightning strike (a natural event) or by a spark from a hot engine (an accident caused by people). Imagine dedicating your life to the study of a particular type of disaster. There are people who do just that. They do this because if we can understand why an event happens, we can help reduce the pain and suffering which may otherwise occur. Disasters in Australia The Commonwealth Government says a disaster has occurred `when the normal community and organisational arrangements cannot cope with a hazard impact'. Another definition is that a disaster is a condition or event of significant destruction, disruption or distress to a community. In this course, we define a disaster as events associated with large-scale environmental or structural damage and/or loss of life. Whichever definition we use, a disaster is not good news. Part of life is thinking ahead and making sure we minimise the impact disasters may have. We can classify natural disasters as shown in the following table. We will look at disasters where humans help cause the problem in the next unit. Although natural disasters cause more than $1 billion in damage each year, Australia is not affected as badly as many nations. This is partly due to the Australian continent being geologically stable and not prone to major earthquakes. It is also due to our relatively small population. Our worst disasters are due to meteorological 'causes. Adverse weather, such as tropical cyclones, bushfires, floods, droughts, heatwaves, severe wind and rain storms, hail and tornadoes, occurs frequently in Australia. Heatwaves have cost the most lives, with more than 400 people dying in a heatwave in 1939. Today, most people are prepared for such events and there is little loss of life. Severe cyclones occur in the less populated far north while storm surges affecting urban areas occur less frequently. However, bad weather causes regular disruptions to work and transport, and costs hundreds of millions of dollars of damage annually. Severe droughts occur roughly once or twice a decade and usually last for extended periods. The greatest overall economic damage is caused by flood and drought. Other disasters are caused by geological forces. The Australian continent is relatively geologically-stable as it sits in the middle of a crustal plate. As a result, it is less likely to experience adverse geological hazards such as earthquakes, tsunamis, landslides and volcanoes. The same is not true for New Zealand, Papua New Guinea and Indonesia, which are located along the edges of crustal plates. Moderate-sized earthquakes, however, do occur in Australia. In December 1989, the Newcastle earthquake resulted in 13 deaths and 160 injuries and the damage bill was well over $4 billion. Tsunamis (incorrectly called tidal waves) are rare in Australia. An earthquake in Chile in 1960 produced a tsunami that damaged the eastern seaboard and there were other tsunamis in 1977 and 1994 along the north-west coast of Western Australia. There are no active volcanoes in Australia, and landslides in Australia are usually the result of soil saturation and human activity. Although presenting a very low risk, disasters are possible due to extraterrestrial comets or asteroids. If such large masses were to collide with the Earth, it could cause a major regional disaster or even a world-wide catastrophe. There are many past impact sites in Australia, such as the Wolf Creek crater in Western Australia. Such impacts in the past are believed to have caused the extinction of the dinosaurs amongst many other species.


In terms of cause of death, the most serious disasters have been biological. The great influenza epidemic in 1918 killed more than 10 000 Australians. The AIDS epidemic has so far cost at least 20 million lives worldwide. Modern hygiene and medicine has greatly reduced the impact of disease, but not eliminated the problem. Human disease epidemics, such as influenza, Ross River fever, Hepatitis and AIDS, still occur. Agriculture is damaged by vermin and insect plagues, such as rabbits, mice and locusts. Various exotic animal diseases, such as `foot-and-mouth' and anthrax do not occur in Australia but would devastate the economy if they were to enter the country. Food-crops can suffer from fungal and bacterial disease epidemics. Australian Natural Disasters


Natural Hazards


§ gather and process information from first-hand and secondary sources to identify insurance compensation for natural disasters to discuss the definitions and terminology used in insurance contracts Disasters and Insurance We can all afford to replace some items that are damaged or destroyed. If you break a cup or drop a bottle of soft drink, the financial consequences are not great. But what happens if your car crashes, the home burns down or the person who earns the family income dies? Very few people can afford to replace cars, homes or an income. That is why people and businesses should insure against those financial losses that they cannot reasonably afford to suffer. It can get worse. Suppose you have borrowed money for the house or car. If the house is destroyed or the car is stolen, you could owe money on items you no longer have! Most people take out insurance in the following areas: • motor vehicle insurance • house insurance • contents insurance • life insurance. Businesses will have additional insurance cover. Unfortunately, 30 per cent of Australians do not have building or contents insurance. Of those people who do have such insurance, 40 per cent do not have enough insurance to replace the house or contents. We will look at home and contents insurance. There are two main types of contract. A defined events policy is usually cheaper and sets out a list of what is and is not covered by the insurance policy. You need to read these policies carefully. During the 1986 western Sydney floods, many people found that their policies did not cover all the damage. If the water entered their houses through a hole in the roof due to storm damage, they were covered. But if the water entered the house under the door as a result of flood waters from local creeks, they were not covered. The alternative more expensive coverage is called an accidental damage policy. This is a much broader coverage, and only lists those things that are not covered. Thus, if you spill a can of paint on the carpet, it will be covered by an accidental damage policy unless it is specifically listed as not covered. The next difference is in how you will be reimbursed if you make a claim. The best but more expensive method is called a replacement policy or new-for-old policy. If the house burns down it will be replaced by a new one to the same standard. If a camera is stolen, it will be replaced by a new one of the same type. The other type of policy is cheaper and is called an indemnity policy. With this type of insurance, you receive the value of the goods at the time they were stolen. Thus if a 10-year-old TV was stolen, you receive enough money to buy another 10-year-old TV but not a new one. The tables below lists many other terms found in insurance policies. Although based on information from one company, most other companies will have similar terminology.


Questions Natural Disasters: 1 Which of the following is an example of a disaster? (A) Your favourite CD is scratched. (B) A bushfire burns the local bush. (C) Your CD player is stolen. (D) Your house is destroyed in a bushfire. 2 Which of the following is a meteorological disaster? (A) Lightning destroys power supplies to a city. (B) A tsunami caused by an earthquake destroys coastal towns and suburbs. (C) An earthquake causes a massive landslide that buries a small city. (D) Foot-and-mouth disease infects cattle in a country. 3 Which of the following disasters causes the greatest loss of human life in Australia? (A) Volcanic eruption. (B) Heatwave. (C) Floods. (D) Drought. 4 Which of the following disasters causes the greatest financial loss in Australia? (A) Earthquake. (B) Volcanic eruption. (C) Floods. (D) Heatwave. 5 What is the meaning of the term `excess' in an insurance policy? (A) The extra premium you must pay because a person is young. (B) The amount you pay when you make a claim on a policy. (C) The amount of money received to ensure new-for-old replacement. (D) The extra that must be paid for an accidental damage policy. 6 Define the term `disaster'.

7 Identify three types of natural disaster, and identify a specific Australian example for each one.

8 (a) Identify why people insure themselves against a disaster.

(b) Discuss the definitions and terminology used for the two major types of home and contents insurance.

9. For a named Australian natural disaster, answer the following questions.

(a) When did the natural disaster occur?

(b) Where did the natural disaster occur?

(c) What were the consequences of the disaster?

(d) Which techniques have been employed to reduce the incidence of damage next time?

(e) What techniques have been employed to monitor disaster in the future?


Disasters and Human Activity Ocean liners eventually end their useful lives. Thus the 5400-tonne, 125-metre-long former trans-Tasman liner Maheno was sold to Japan for scrap metal. On 9 July 1935, while it was being towed to Japan, it was hit by a cyclone off Fraser Island. The tow rope snapped and the Maheno was driven ashore on 19 July 1935. All that remains is a rusting hulk. Disasters Caused by Humans There was an element of bad luck in the Maheno wreck. Cyclones do not normally occur in July. Other disasters are caused by humans. Some of these are politically and religiously inspired. These can include terrorist bombings (for example, Bali), riots that destroy vehicles and buildings; shooting massacres (for example, Port Arthur, Tasmania), and sabotage of essential services (for example, water or power supplies). Other disasters occur at mass gatherings such as sporting matches, pop concerts and dance halls when people are killed and/or injured in crowd-crushes. Managerial incompetence, corruption and cost cutting have all contributed to major disasters. Because Australia is an industrialised nation, it is at risk from technological hazards and accidents, which sometimes become disasters. Major transport accidents, such as the Granville train disaster in Sydney, were at least in part due to poor maintenance. Mining disasters that have led to underground explosions have been traced to poor management and cost-cutting (for example, Moura coal mine, central Queensland). Hazardous materials can lead to disasters (for example, oil or chemical spills) - some are accidents while others can involve deliberate dumping of toxic materials. Occasional collapses of buildings and bridges are caused by human error (for example, 'Westgate Bridge'. Melbourne and 'Tasman Bridge', Hobart). In some parts of the world dams have failed due to poor design, and nuclear accidents have spread radioactive material in Chernobyl (Ukraine) and Three Mile Island (United States).The re-entry of space debris to Earth has the potential to cause a disaster (for example, Skylab, Western Australia, 1979). Essential services are often severely disrupted by accidents, cost-cutting and poor design. They have caused significant economic and social disruption and have the potential to cause loss of life. The city of Auckland in New Zealand in February 1998 was without power for three months when power cables burnt out. Management with little knowledge of electrical power, poor maintenance and cost-cutting all contributed to the problem. In July 1998, some sections of Sydney's water supply became contaminated by harmful bacteria. The crisis continued for more than two months until the source of the problem was identified. Poor management of water catchments, including the leakage of sewage into the catchment all contributed to the problem. In September 1998, a gas refinery explosion at Longford in Victoria killed two and injured eight other workers. This left Victoria without gas supplies for a period of two weeks. The massive disruption to commerce and industry cost more than a billion dollars. Poor management and a failure to train employees were found to be responsible. Nature and Human Activity Combined Other disasters are a combination of the effects of nature magnified in some way by human activity. Thus, dust storms are a combination of drought and problems in the management of agricultural land. According to the 1996 State of the Environment Report, the annual frequency of dust storms across Australia has decreased since the 1970s, mainly as a result of improved rabbit control and the adoption of conservation farming. However, there is still a legacy of poor farming practices. In some areas the land is still highly degraded. The dust storms of September 2002 were in large measure the result of

Westgate Bridge


massive drought. Tens of millions of tonnes of topsoil, or an estimated two million semi-trailer loads of dust, were blown across the eastern side of the continent. Another place where natural and human activity can combine is landslides. In Australia landslides are usually the result of soil saturation and/or human activity. In 1988 and 1997 two landslide disasters claimed many lives in New South Wales. Coledale is a small coal-mining community near Wollongong. After two weeks of heavy rainfall a 20-metre high railway embankment collapsed killing a woman and her infant son in a house below. The area was prone to subsidence and evidence given at the inquest showed that the embankment had not been designed properly to take account of this. In July 1997 Australia's worst landslide occurred at Thredbo Ski Village in the New South Wales Alps. A large section of steep mountainside below the Alpine Way road collapsed. About 1000 tonnes of earth, rock and trees slid rapidly down the steep slope and destroyed two ski lodges. One survivor was recovered from the debris, but 18 people were killed. This disaster also caused damage worth many millions of dollars. An inquiry established that building had been allowed on very unstable slopes and that there had been poor maintenance on the Alpine Way above the ski lodges. It can often take a long time to get authorities to act. One such case was the building of the Cape Wickham Lighthouse on the northern tip of King Island. Sailing ships coming thousand of kilometres from the Cape of Good Hope had to find a gap 84 kilometres ie between Cape Otway in Victoria and Cape Wickham! Not surprisingly there are many shipwrecks along the coasts of Victoria and King Island. The loss of the Neva with 225 lives, mainly convict women and children in 1835, had brought no reaction from authorities. It was Australia's largest maritime disaster, the wrecking of the Cataraqui with the loss of 400 lives in 1845, that eventually led to the establishment of Cape Wickham lighthouse. Four hundred emigrants drowned when the ship struck rocks just a hundred metres offshore on the west coast of King Island. The vessel had tried to ride out a storm west of King Island as the bad weather had prevented accurate navigational observations. With increasingly poor conditions, the Cataraqui resumed sailing eastward and on the following day the vessel struck rocks on the south-western coast of King Island. Even after the building of the lighthouse there were still wrecks along the coast. Some ship's masters mistook the Cape Wickham Lighthouse for the Cape Otway Lighthouse that was much further north! Modern transport systems provide many opportunities for nature and humans to combine to produce a disaster. Australia has been spared any very serious aviation disasters. New Zealand has not been so fortunate. In 1979 an Air New Zealand DC 10 on a flight over Antarctica crashed on Mount Erebus, with the loss of 257 lives. During an inquiry Air New Zealand attempted to put the blame on pilot error. This was dismissed by the official report as `a pre-determined plan of deception' and `an orchestrated litany of lies'. The report found that `the single dominant and effective cause of the disaster was the mistake made by those airline officials who programmed the aircraft to fly directly at Mount Erebus and omitted to tell the air crew'. So the pilots believed they were flying on route safely down McMurdo Sound, west of Mount Erebus, when in fact they were headed directly towards the mountain. The whiteout weather conditions of the time made Mount Erebus invisible!


Questions: Disasters and Human Activity. 1 Which of the following disasters involves human activity? (A) Earthquake. (B) Volcanic eruption. (C) Mine explosion. (D) Cyclone. 2 In 1970, Melbourne's Westgate Bridge collapsed during construction killing 35 workers. How would you classify this disaster? (A) Natural causes. (B) Human activity. (C) Natural causes combined with human activity. (D) Pure accident. 3 After the building of the Cape Wickham lighthouse, at least three ship's captains thought it was the Cape Otway lighthouse and sailed further south only to be wrecked on the coast of King Island. How would you classify this disaster? (A) Natural causes. (B) Human activity. (C) Natural causes combined with human activity. (D) Pure accident. 4 Which of the following disasters causes the greatest loss of human life in Australia? (A) Dust storms. (B) Landslides. (C) Train crashes. (D) Shipwrecks. 5 Which of the following disasters causes the greatest financial loss in Australia? (A) Loss of a state's gas supplies. (B) Collapse of a bridge. (C) Crash of an aeroplane. (D) Terrorist bombings. 6 Identify three types of disaster associated mostly with human activity using specific Australian examples.

7 Identify a specific Australian example where nature and human activity have combined to produce disastrous dust storms.

8 Identify a specific Australian example where nature and human activity have combined to produce a disaster, such as a shipwreck.

9 Identify a specific Australian example where nature and human activity have combined to produce a disaster such as a landslide.

10 Nearly 2000 people a year are killed on Australian roads. Do you think this should be called a disaster? Justify your answer.


– define the term ‘atmospheric pressure’ and describe the movement of air currents between areas of high and low pressure

– describe technological advances that have contributed to increased understanding of meteorology – describe the relationship between the monitoring of weather patterns by radar and laser light and the

analysis of reflected wave patterns by computers

Studying the Weather Air pressure, temperature, rainfall, humidity and wind speed have been measured and used to predict weather conditions for several hundred years. A traditional weather station is called a Stevenson's screen and provides constant measuring conditions. A person needs to be present to make measurements every day. However, in many remote parts of Australia there are few if any people. That is why around 200 automated weather stations are located around Australia. They communicate their measurements to central computers via landline or satellite. Not only can they be located in remote parts of Australia, they can also be located on buoys in the middle of the ocean. In recent decades, weather radar and satellite measurements have also helped improve our ability to measure the weather. Air Pressure Why does the air move? Why do we have winds? Why do storms and cyclones move across the country? To understand, we need to know a little about air pressure. Pressure is the amount of force per unit area. It is measured in Pascals where one Pascal is one Newton per square metre. We meet the idea of air pressure at the service station when checking the air pressure in car tyres. In this case, it is expressed as Newtons per square centimetre. When studying the weather, air pressure is measured in hectopascals (hPa) where 1 hectopascal is 100 Pascals. Air pressure at sea level fluctuates around 1013 hectopascals. It can drop to 970 hPa during severe storms. In a high pressure system it can reach 1040 hPa. Air pressure is measured on a barometer. A practical barometer was invented by Evangelista Torricelli in the 1600s. It consisted of a tall glass tube sealed at one end. The tube was filled with mercury, and then inverted to stand in a bowl of mercury. This created a vacuum at the sealed end of the tube. To test the instrument two French scientists carried it up a mountain. They found that, as they climbed, the height of the mercury column became smaller showing the air pressure dropped. Mercury is too dangerous for you to use in the laboratory, but you could construct a similar device using water and observe how the height of the column changes over a few days. It should rise during high pressure and drop due to low pressure. However, temperature can also change the height of the water due to expansion and contraction.

Weather measurements A Stevenson's screen is a traditional weather station.

Aneroid barometer Changes in air pressure are shown on the dial.


More modern aneroid barometers work in a different manner. Inside is a flexible box to which the needle is attached. As air pressure changes the size of the box, the needle moves. You can see the effects air pressure can have on the size of containers using an empty drink can. Wearing safety glasses, one-quarter fill the can with water and bring it to the boil. Using tongs, quickly invert the hot can over a trough or bucket of cold water. The steam forces a lot of the air from the can. When inverted in cold water, the steam condenses and reduces the air pressure inside the can. The air pressure outside remains constant, and as it is now much larger than the pressure inside, it collapses the can. Weather Satellites Modern weather satellites have become essential for weather forecasting. Not only do they provide the images of cloud cover that we see on TV weather reports and in newspapers, but they are also essential to climate research. Geostationary meteorological satellites are placed into an orbit that is just below 36 000 kilometres above the Earth over the equator. Because they take 24 hours to orbit the Earth, the satellites remain at the same spot on the equator. The Japanese Geostationary Meteorological Satellite (GMS-5) over Indonesia has provided images for Australia over many years. It should be replaced by a new satellite by the time you read this. Images also come from the Chinese Feng Yun-2B satellite. All these satellites provide infra-red and visible light photographs of the Australian region (Figure 3.5). Visible light is used to take photographs of the Earth and its clouds during daylight hours. Infra-red images can be taken day or night and measure the temperature of the surface of the Earth and clouds. Successive images provide a picture of cloud movements across Australia and

Torricelli's barometer As air pressure changes, the height of the mercury column changes.

Meteorological satellites Some of the satellites are geostationary while others orbit over the poles.

Satellite images


nearby regions. The movements of clouds also allow wind speeds to be calculated. Regular satellite images are also used to track the movements of cyclones. Satellites that pass over the polar regions are placed in orbit at an altitude of about 850 kilometres. These satellites take around 100 minutes to orbit the Earth. Although the orbit of the satellite remains fixed in space, the Earth spins beneath so that the satellite passes over a different portion of the Earth each 100 minutes. Thus, polar-orbiting satellites such as the United States' NOAA series can photograph a given point on the Earth's surface at the same time each day taking measurements at several wavelengths. Photographs are taken in both visible light and infra-red. Since the polar-orbiting satellites are much closer to the surface of the Earth, they provide more detail and allow measurements not possible for geostationary satellites. Over land, satellite images allow the fog levels near airports to be determined, permit the extent and movement of floodwaters to be tracked, and determine the extent of snowfields in the Alps. In Antarctica, the extent and movement of pack-ice is possible. Bushfires can be monitored and the state of vegetation before and after rain determined. Away from land, sea surface temperatures and roughness of the oceans in storms can be measured. Table 3.1 lists the range of measurements that can be taken from weather satellites.


Weather Radar There are more than 40 sites around Australia with weather radar. Not only is such radar found near our major cities, but northern coastal areas subject to tropical cyclones are also covered. The radar allows the movements of clouds, rain and storms to be tracked, and makes it possible to determine the severity of the storm. Radar can show light rain to a distance of around 150 kilometres, and severe thunderstorms to over 400 kilometres, limited mainly by the curvature of the Earth. Radar uses the microwave section of the elctromagnetic spectrum. The microwaves have a wavelength of around 10 cm. At this wavelength, the radar is scattered from rain, hail and snow but not from cloud. The radar dish sweeps systematically across the sky. As it does so, a narrow microwave beam is sent out. When the microwaves strike rain, hail or snow they are reflected back to the radar. Since we know the speed of light, once the time between the sending of the microwave pulse and its arrival back at the radar has been measured, the distance can be calculated using a computer. The intensity of the reflected beam allows the severity of the storm to be measured. This data is then plotted by the computer onto a map. Modern weather radar uses the Doppler effect to measure the movement of the storm. The Doppler effect is also used by the police to measure the speed of cars. When a radar beam reflects from a moving object, its frequency and wavelength is changed. Modem electronics allows these small changes to be measured, and computers calculate the speed before plotting the data onto maps. Radar images show the location of rain compared to features such as the coastline and major towns. Different colours are used to indicate rainfall intensity. For example, royal blue represents light drizzle, while red is used to depict very heavy rain (possibly containing hailstones). There are six levels of rainfall intensity shown on the key below each radar image. In northern Australia, weather radar allows the movements of cyclones to be tracked. Laser Measurements Satellite images and radar images can be used to track the movement of clouds and hence the air around them. This cannot occur in air that has no clouds. Thus, a large gap in our understanding of the world's weather and climate is knowledge of wind speeds and directions in clear air. However, even clear air does contain small dust particles and fine droplets called aerosols. To measure the movement of the wind, we

Weather radar (a) Radar sends out pulses of microwaves. (a) Pulses are reflected from water, hail and snow.


measure the movement of these tiny particles. This is achieved using an infra-red lidar (Light Detection and Ranging). The wavelength is small enough to be scattered from such particles. The instrument uses the Doppler effect to help determine direction and speed in which the particles are moving. One type of lidar is located on the ground. The infra-red laser light is fired vertically, and the small amount that is reflected from clouds or fine particles is collected in a telescope and recorded. The time between pulse and echo will (like radar) determine the distance to an object. The change in wavelength or frequency allows speed and direction to be calculated. The analysis is carried out by computers and presented on a map. As well as the movement of clear air, the device can be used to measure the altitude of clouds and the levels of pollutants such as ozone that are in the air. The major problem with ground-based lidars is that they do not readily provide three-dimensional data. A lidar system aboard an Earth-observing satellite allows such measurements to be carried out. The satellite fires pulses of eye-safe infra-red laser light into the atmosphere and measures the light that is reflected back to it by dust and aerosols in the atmosphere. At the same time a vertical reference beam is used to measure movements of the satellite itself. Computers use the data to produce three-dimensional maps of wind movements. This technology is still in its developmental stage and is not yet widely used for weather forecasting. Questions: Studying the Weather 1 What advantage is an automatic weather station? (A) It is much more accurate than weather stations where the readings are taken by scientists. (B) Australia has no people trained to make measurements of weather conditions. (C) Weather records can be gathered from locations where there are few if any people. (D) Telephone links cannot transmit the type of data collected. 2 What name is given to a device used to measure air pressure? (A) Thermometer. (B) Barometer. (C) Clinometer. (D) Odometer. 3 Which of the following readings is closest to normal air pressure at sea level? (A) 970 hPa. (B) 1000 hPa. (C) 1010 hPa. (D) 1040 hPa. 4 Why does a satellite in a polar-orbit produce more detailed weather images than one in a geostationary orbit? (A) Polar-orbit satellites are of higher quality. (B) The polar-orbit satellites are moving relative to the surface of the Earth. (C) Polar-orbit satellites are moving much faster than geostationary satellites. (D) The polar-orbit satellites are much closer to the surface of the Earth.

Lidar Measurements are made from the ground and from satellites


5 Modern radar and lidar can both make use of the Doppler effect. What advantage does Doppler radar and lidar have over other types?

(A) Movement can be measured. (B) A clearer image is produced. (C) Objects further way can be measured. (D) Doppler devices are not affected by the curvature of the Earth.

6 Define the term `atmospheric pressure'. Identify the units used for air pressure on weather maps.

7 Describe two technological advances that have contributed to increased understanding of meteorology.

8 Radar can be used to plot the movements of weather patterns. (a) Explain how radar makes use of reflection.

(b) Describe how the distance to a hailstorm can be determined.

(c) Describe how computers are used to present this information in a usable form.

9 Explain what can be learnt from satellite photographs of cloud patterns.

10 Describe an experiment that you have carried out to demonstrate the effect of differences in air pressure.

Disasters - LMHS Science Classroom...

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