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Unlock This CourseIf your Section B topic is Hazardous environments, your enquiry is an investigation of the physical processes involved in an extreme weather event through the recording of primary and secondary fieldwork evidence. As in the River Fieldwork Enquiry lesson, you need quantitative and qualitative primary data, and at least two different secondary sources. The theory of hazards is in the Hazardous Environments lessons, for example Tropical Cyclone Characteristics. This lesson is about collecting and using the evidence.
An extreme weather event is a storm, a heatwave, a spell of very heavy rain or similar, far from the normal weather for the place. Because you cannot know when one will happen, a school usually studies an event that has just happened, or one that is on its way.
Key terms:
The spec suggests two sets of quantitative methods for this enquiry.
Record the weather at the same times each day. Measure wind speed and direction, rainfall, temperature and air pressure. Also use local risk and hazard maps, which show which streets or areas are most likely to be affected, such as places that flood.
Ask local people a structured set of questions about the hazard. For example, "How serious is the risk of flooding where you live?" with answers on a scale from 1 (not serious) to 5 (very serious). Ask every person the same questions so you can count the answers.
A weather diary for a storm records air pressure every 6 hours: 1012 hPa, 1004 hPa, 996 hPa, 988 hPa. Wind speed at the same times is 10, 22, 35 and 48 km/h.
Pressure falls by 1012 − 988 = 24 hPa while wind speed rises from 10 to 48 km/h. The wind gets stronger as the pressure falls.
In a questionnaire, 40 people are asked whether flooding is the main risk to their street. 28 say yes.
28 ÷ 40 × 100 = 70%. Seven in ten people see flooding as the main risk.
The weather diary tells you what the storm did. The questionnaire tells you how people saw it. Both are numbers you can show on a graph.
A series of images from before, during and after shows how the place changed and how quickly it recovered. They back up the numbers in your diary.
Never go out into dangerous weather to collect data. Take your readings and photographs from a safe place, such as a window or a school building, and stay away from floodwater, fallen branches and power lines. Collect the "after" images only when it is safe. This is part of your risk assessment.
The spec suggests two secondary sources.
An online feed from a local weather station, such as Wunderground. It gives wind, rainfall, temperature and pressure readings through the whole event, even in the hours when you cannot safely be outside.
Local secondary data on weather events. News reports and online accounts describe the damage and how people were affected. Social media is covered in the Using Social Media for Impact Assessment lesson.
You can compare your own diary with the weather station feed to check your readings. Newspapers may exaggerate, so note who wrote the report and why.
You may find that the strongest winds or the heaviest rain come when the pressure is at its lowest. You may find that the areas on the risk map really were the ones affected. Your questionnaire may show that people who were affected before see the risk as more serious. Not every result will fit. A reading taken in a sheltered spot, or a badly worded question, can cause an odd result, and a good answer suggests a reason.
An unfamiliar question gives you new data about an extreme weather event, collected with the same kinds of methods. You should be able to:
A student studied Storm Marlow in a coastal town. The table shows data from the weather station.
| Time | Air pressure (hPa) | Wind speed (km/h) | Rainfall in the last hour (mm) |
|---|---|---|---|
| 06:00 | 1010 | 15 | 1 |
| 12:00 | 998 | 40 | 6 |
| 18:00 | 985 | 72 | 14 |
(a) Describe how wind speed changes between 06:00 and 18:00. [2 marks]
(b) The student took photographs before, during and after the storm. Give one way the photographs could be used. [2 marks]
(c) Explain how newspaper accounts could help the student investigate Storm Marlow. [2 marks]
(d) Suggest one reason why the questionnaire results might be unreliable. [2 marks]
(a) Wind speed increases (1), from 15 km/h at 06:00 to 72 km/h at 18:00 (1).
(b) They can be annotated to show the changes caused by the storm (1), such as damage that was not there in the before photograph (1).
(c) They describe the damage and how people were affected (1), which gives evidence the student could not collect alone, such as events overnight (1).
(d) Only a small number of people may have been asked (1), so a few unusual views could change the results (1).
In (a), a pattern answer needs a start and end figure with units. Say "increases" and give the numbers.