Video: How do high pressure events affect the UK?

﻿Hello geographers, I'm Miss Sully and welcome to your geography lesson. This is lesson six out of 11, on the weather and climate unit. In today's lesson, we will be looking at how high pressure weather events affect the UK, and if that's a good thing or a bad thing. For today's lesson, you will need a pen, paper, and a ruler. So please feel free to pause the video now to get yourself organised, and use that time to clear any distractions away. Great, now that you've got everything that you need, let's write today's title at the top of our page. And that title on the screen and it says, how do high pressure events affect the UK? So pause the video to get that written down. Okay, now that's done, let's get started. Air moves above the Earth's surface due to different air pressure. A pressure movement is caused by different temperatures. Hot air rises as it's less dense, and cool air sinks as it's more dense, which means heavy. When air cools, it sinks down towards the Earth's surface adding pressure. So which of the following statements is true? Is it option one, high pressure is when warm air descends as it's less dense. Option two, high pressure is when warm air descends as it's more dense. Option three, high pressure is when cool air descends as it's less dense. Or is the option four, high pressure is when cool air descends as it's more dense. So shout out the answer in three, two, one, correct. It's option four. So pause the video to write the statement down. Different air pressures lead to different weather conditions. Low pressure is when warm air rises, cools, condenses, which forms clouds and leads to rainfall. However, high pressure leads to a low cloud cover as the air has descended, which means no rainfall, clear skies means more intense sunlight, which means hot weather in summer, and very cold weather in winter. In the summer, there are no clouds in the sky, which means the sun will be more intense and lead to hotter temperatures. However, as there is no clouds to trap the heat, it gets colder in the evenings. As a result, dew may form as water vapour condenses. You might have noticed grass feeling wet on summer mornings, after it being dry overnight. So this is why. If high pressure events are prolonged, the lack of rainfall can lead to drought. High pressure weather systems in summer leads to; is it option one, clear skies, hot days and cool evenings. Option two, clear skies, cold days and cool evenings. Option three, clear skies, hot days and hot evenings. Or is it option four, cloudy skies, hot days and cool evenings. You five seconds to choose the correct answer. Three, two, one. So the correct answer is option one. High pressure weather systems in summer leads to clear skies, hot days and cool evenings. So please pause the video to write that down. In winter, high pressure weather systems also leads to clear skies, but with cold and bright weather. Water on roads can freeze as the sun goes down, turning it into ice. With no clouds cover, the ground cools fast at night and cools the air above it. Water vapour condenses and freezes on surface leaving frost. High pressure weather systems in winter leads to; is it option one, cloudy skies, rainfall and flooding. Option two, clear skies, rainfall and drought. Option three, clear skies, bright days and freezing evenings. Or option four, cloudy skies, hot days and cool evenings. So again, shout out your answer in five seconds. Three, two, one. Correct, it's option three. So high pressure weather systems in winter leads to clear skies, bright days and freezing evenings. So let's pause and test our understanding on high pressure systems in summer and winter. The question asks, describe the weather conditions associated with high pressure systems in summer. Let's have a look at a model and say it together. The higher pressure system brings clear skies in summer with hot temperatures in the day and cool temperatures in the evening. As a result of the cold temperature, dew can form on the grass. The higher temperatures and clear skies can also lead to droughts. And drought is very dry periods. It's now your turn to write the answer to the question. Describe the weather conditions associated with high pressure systems in winter. So you need to write the sentences on the screen, and fill in the gaps with the options below. Pause the video to complete the task. Great work. So the answer is, the high precious system brings clear skies in winter with cold temperatures in the day, and freezing temperatures in the evening. Due to this, water vapour condenses and freezes on surfaces, leaving frost. So give yourself a tick for each one that's correct, and make any amendments if needed. Air pressure is shown on a weather map using isobars, which are the lines that overlay the map of the UK on the screen. As you can see, there are different numbers at the end of each line. Each number represents atmospheric measures in millibars, and the line joins together places of equal atmospheric pressure. So for example, the isobar most North represents 1008 millibars, and anywhere along that line does too. Isobars tend to vary from 890 millibars, which is the atmospheric pressure of a hurricane, which is a large area of low pressure, to 1060 millibars the atmospheric pressure of an anticyclone, which is a large area of high pressure. Therefore, a higher number represent high pressure. As you can see, isobars increase in the same intervals, which is four millibars. Also the closer the isobar, the wintier it is. Included in the map key, we can see symbols that we've looked at in previous lessons, within the weather and climate unit. They are seen on the map, are both Edinburgh and Birmingham. Cloud cover is represented by the circles, wind strength, which is shown by the lines coming from the circles, which look a little like keys you use to open doors. And finally we have temperature in degrees celsius represented by the number. Using your understanding, answer the following questions. Choose Birmingham or Edinburgh to answer the following questions. Number one, Where is the highest air pressure? Where is the most cloud cover? And where is the wind strength the strongest? So pause the video to complete the task. Edinburgh is located between 1020 millibars and 1024 millibars, whilst Birmingham is located between 1024 and 1028 millibars. This means that Birmingham is the location with the highest air pressure as the numbers are bigger. For the second question, we need to be looking at the cloud cover in the key. We can then compare the cloud cover over both locations. Edinburgh is two eighths covered, whilst Birmingham is one eighth covered. This means that although in both places, there is little clouds cover, Edinburgh is experiencing cloudier skies. Finally, for wind strength, we also use the key. We can see Edinburgh is 15 knots, and Birmingham is five knots. Therefore, the wind strength is strongest in Edinburgh due to the lower air pressure. There are many advantages to the weather that high pressure brings, and advantages mean good and positive things. In the summer, high pressure will make the weather hotter, and this will mean more people will go to beaches and spend money within the tourism industry. Also high pressure is good for farmers growing crops and this results in more profit for farmers, and increase in local grown fruit and vegetables. However, there are disadvantages. So this means the negatives and bad things about high pressure systems. If hot weather persists, it can result in water shortages. This means some restrictions might be put in place such as hose pipe bans. Hot weather can lead forest fires, and you may remember the forest fires that lasted months in Australia. We can also have forest fires in the UK. This can result in people and wildlife being at risk. Ice on roads can make them more dangerous and result in more accidents, meaning people are at risk. And extreme cold weather can leave the elderly more vulnerable to hypothermia and illnesses. So we've now arrived at our main task. Can you please draw the table that's on the screen by splitting your page in half and writing advantages on one side, and disadvantages on the other. So pause the video to make sure you have that table ready. Great. Now you need to categorise the statements into the table. Pause the video to complete the task. Excellent work. Check your answers against mine. If you've put something in the wrong column, just draw an arrow over to the other side. Remember to give yourself a tick for every one that you got correct. Now that we've been able to categorise the statements into advantages and disadvantages, we need to be able to explain them. So let's have a look at an example of an advantage. In the UK, high pressure weather has a positive impact for growing plants and for farmers. This means that more people will be able to buy locally sourced plants and vegetables. So I've explained why that's good, but I've carried that on again. This means that farmers will make more profit, which can help boost the economy. So I've explained twice that. It's now your task to explain the disadvantage impact. So high pressure weather can have a negative impact in the winter as the elderly can be at risk of hypothermia due to the drop in temperature. This means that... So pause the video to finish that sentence. Great work. Here's an example of what you could have written. This means that there will be added pressure on health care such as the NHS. As long as you've explained why the impact is bad, give yourself a tick because this is just one example of what you could have written. So that's it for today's lesson. We've learned that high pressure systems bring warm and dry weather in summer, and clear and frosty weather in winter and how that can bring both positive and negative impacts to the UK. We've also learned that air pressure is shown as isobars on climate maps. Next lesson, we'll be looking at the impact of low pressure systems on the UK. Excellent work today. I'm so proud of you. Bye.

Exit Quiz: How do high pressure events affect the UK?

Completed: How do high pressure events affect the UK?

In this lesson, we will be learning about the impact high pressure systems have on the UK. We will be focussing on the weather conditions and the advantages and disadvantages of these.

Geography

How do high pressure events affect the UK?

Video

Final Quiz

Lesson Complete