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Name: Form: Y6 Weather III Brambletye Geography Department Name: Form: Contents: NOTE: This booklet should be kept for revision notes for Year 7 and Year 8. Traffic Light Section 1. 2. 3. 4. 5. 6. 7. 8. A E Wind: an ‘element’ of the weather The Beaufort Scale The Atmosphere Why does the wind blow? Where does our weather come from? Anticyclones Depressions (page 1) Depressions (page 2) What do my marks mean? Key to traffic lights: I do not understand this I understand most of this I understand this really well Accuracy: How well have you completed the task? 0 = not done; 5=excellent Effort: A= 5 E= 5 Have you tried your best? 0 = no!; 5=excellent work The topic that I enjoyed the most was ……………………………………………………………………………………. The topic that I found the easiest was …………………………………………………………………………………… The topic that I found the hardest was ………………………………………………………………………………….. Please complete this page at the end of the term. 2 Y6 Weather III Brambletye Geography Department 1. Wind: an ‘element’ of the weather Wind is one of the ‘elements’ of the weather. It is not an element in scientific terms, but one of the phenomena in the atmosphere that we can observe and measure. “Weather is ________________________________________________ _________________________________________________________” Warning: Do not confuse weather and climate! “Climate is the general type of weather that an area experiences” Note: Climate is normally calculated on a 30 year average Climate normally focuses on rainfall and temperature and how they change month by month “Wind is ___________________________________________ _________________________________________________________” There are two features of wind that we can measure: the direction that it is moving in and the speed that it is travelling in. The photograph on the right shows the equipment that is used to measure wind on a weather station. The arrow on the left points the direction that the wind is coming from. The speed that the cups rotate, tell us how fast the wind is blowing. Wind speed is measured in …………………………… using a …………………………………… Wind direction is measured in ……………………….. using a ……………………………………. 3 Y6 Weather III Brambletye Geography Department 2. The Beaufort Scale The Beaufort Scale If you do not have an anemometer, then wind speed can be measured by looking at the way that the wind affects the world around you. What is the difference between a ‘gentle breeze’ and a ‘light breeze’? In 1805, Francis Beaufort, an officer in the Irish Navy suggested a scale that could be used to measure wind speed without expensive equipment and, more importantly he standardised the words that were used to describe wind. His scale ran from 0 (no wind at all), to 12, a devastating hurricane. 4 Y6 Weather III Brambletye Geography Department My Beaufort Scale A= E= On the grid, below design your own Beaufort Scale and draw a diagram to show what happens in each step. 5 Y6 Weather III Brambletye Geography Department 3. The Atmosphere The layer of gases that surrounds the Earth and separates the surface from the void of space is known as the atmosphere. The atmosphere is held in place by gravity. The Earth's atmosphere contains a mixture of gases is commonly known as air: o 78% nitrogen o 21% oxygen o 0.93% argon o 0.04% carbon dioxide - although this is increasing o water vapour (average of 1% - but that varies) o trace amounts of other gases. The atmosphere is densest at the surface and it gets ‘thinner’ as you go up towards space. Due to the spinning action of the Earth, the atmosphere is deeper at the equator and shallower at the poles. There are a series of layers or ‘spheres’ that you would pass through if you travelled up through the atmosphere: The layers of the atmosphere EXOSPHERE Thermopause 80km Mesopause Stratopause Tropopause 6 Y6 Weather III Brambletye Geography Department The troposphere: The troposphere is the layer closest to the Earth's surface, extending up to about 10-15 km above the Earth's surface. It contains 75% of the atmosphere's mass. Temperature and pressure drops as you go higher up the troposphere. This is the layer where all of the weather happens. The tropopause: At the very top of the troposphere is the tropopause where the temperature reaches a (stable) minimum. Some scientists call the tropopause a "cold trap" because this is a point where rising water vapour cannot go higher because it changes into ice and is trapped. If there is no cold trap, Earth would lose all its water! The Greenhouse Effect: Heat from the Sun warms the Earth's surface but most of it is radiated and sent back into space. ‘Greenhouse gasses’ such as water vapour and carbon dioxide in the troposphere trap some of this heat, preventing it from escaping thus keep the Earth warm. This trapping of heat is called the "greenhouse effect". If it was not for the greenhouse effect, our planet would be a ball of ice and there would be no life on the planet. However, if there is too much carbon dioxide in the troposphere then it will trap too much heat. Scientists are afraid that the increasing amounts of carbon dioxide would raise the Earth's surface temperature, bringing significant changes to worldwide weather patterns ... shifting in climatic zones and the melting of the polar ice caps, which could raise the level of the world's oceans. This ‘enhanced’ greenhouse effect leads to Global Warming and climate change. The Ozone Layer: The stratosphere contains a thin layer of ozone which absorbs most of the harmful ultraviolet radiation from the Sun. The ozone layer is being depleted, and is getting thinner over Europe, Asia, North American and Antarctica : "holes" are appearing in the ozone layer. These holes are created by pollution: especially the use of CFCs in aerosol cans. NOTE: The thinning of the ozone layer does not cause Global Warming! 7 Y6 Weather III Brambletye Geography Department Questions: 1. What is the atmosphere? ……………………………………………………………………………. 2. What is the most common gas found in the atmosphere? …………………………………… 3. What percentage of the atmosphere is oxygen ? …………………………………………………. 4. Where is the atmosphere deepest? ……………………………………………………………………. 5. In which atmospheric layer does all of the weather occur? ……………………………………. 6. In which atmospheric layer do satellites orbit the Earth? ……………………………………… 7. Why is the tropopause important for the weather? ………………………………………………. 8. Why is the ‘greenhouse effect’ important? ……..……………………………………………………. ………………………………………………………………………………………………………..………………. 9. How is the ‘greenhouse effect’ being enhanced? ………………………………………………….. ………………………………………………………………………………………………………..………………. 10. What will the effects of this ‘enhanced greenhouse effect’ be? ………………………………. ………………………………………………………………………………………………………..………………. ………………………………………………………………………………………………………..………………. 11. Why might holes in the ozone layer be considered a bad thing? ……………………..……. ………………………………………………………………………………………………………..………………. 12. How could the effects of global warming and climate change be reduced … a. By industries and governments? ……………………………………………………………….. ………………………………………………………………………………………………………………. b. By you and your family? ………….……………………………………………………………….. ………………………………………………………………………………………………………………. A= E= 8 Y6 Weather III Brambletye Geography Department 4. Why does wind blow? Air pressure and wind: Air has mass. The ‘weight’ of air above your head is the equivalent of an elephant! When the air above us is rising then there is less pressure pushing down on us: this is known as LOW pressure When the air above us is sinking then there is more pressure pushing down on us: this is known as HIGH pressure. Air pressure is measured in …………………………… using a …………………………………… Rising air Sinking air Ground Add the words ‘HIGH’ and ‘LOW’ to the diagram above. Draw and label arrows to show the direction that you expect wind to blow. When air is warmed, it becomes lighter and rises: this is felt as low pressure on the ground. When air is cooled, it becomes denser and sinks: this is felt as high pressure on the ground. Low pressure is generally associated with windy and unsettled weather. High pressure is generally associated with stable weather (hot clear skies in the summer and frosty mornings in winter) Air in the atmosphere always seeks to be at equilibrium (the same temperature and pressure, throughout). Air will always move from an area of HIGH pressure to an area of LOW pressure. The bigger the difference in pressure, the faster the air will move: the quicker the wind. Consequently, watch the school weather station: whenever the air pressure gets below 990mb, you will notice that the wind starts to pick up. When it it gets to around 950mb, it will be very windy indeed! 9 Y6 Weather III Brambletye Geography Department Global winds: There are a series of global air circulations. These air movements are all started by strong heating from the sun on the equator. Draw the global atmospheric convection currents These circulations cause the prevailing winds such as the North Atlantic Drift and the trade North Pole winds. Tropic of Cancer Equator Tropic of Capricorn Local winds: South Pole Local winds: Where there are differences in land cover, there will be differences in heating and winds will be formed. An example of this is onshore and offshore breezes that occur on the coast: describe how coastal winds change during the day. 10 A= E= Y6 Weather III Brambletye Geography Department 5. Where does our weather come from? Our weather in the British Isles is controlled by a series of huge ‘lumps’ of air known as air masses. These are generally high pressure areas with stable conditions. o The air in these areas take on the regional climate characteristics (mainly in terms of temperature) o As the air travels towards the British Isles it picks up characteristics from the route that it takes (mainly moisture if it travels across an ocean) The spinning of the Earth and National weather conditions suck air across the British Isles from the following places: Air Masses affecting the British Isles Activity: A= E= Complete the table below and then put the correct abbreviations (Abbr.) into the correct circles on the map above. If the air mass is warm, colour the arrow red; if it is cool, colour the arrow blue. bbr. Name Location Characteristics Summer or Winter? TM Tropical Maritime South Atlantic Warm and moist All year around PM P Labrador Sea Polar PC Mainly Winter TC Hot and dry 11 Mainly Summer Y6 Weather III Brambletye Geography Department 6. Anticyclones Anticyclones are areas of high pressure (over 1 bar or 1,000mb – or one atmospere’s worth of air pushing down) Air is sinking in an anticyclone and so they are normally very stable with little wind. They are large weather systems and they move very slowly. Wind travels around an anticyclone in a clockwise direction. Weather forecast for midday Wednesday, 12th May. A= E= 12 Y6 Weather III Brambletye Geography Department 7. Depressions A= E= Depressions are areas of low pressure (under 1,000mb) They are called depressions because the barometer dips when they are overhead. Air is rising in a depression, spiraling anticlockwise and as a result they are unstable systems with high winds, cloudy skies and rainfall. They are quite fast-moving systems and they become stable quite quickly. They occur where warmer air and cooler air meet: fronts. Weather forecast for midday Tuesday 24th April. a. b. c. Air Masses 2. How does the weather come to the UK? a. Depressions b. Anticyclones 13 Y6 Weather III Brambletye Geography Department Cross-section through a depression: Depressions move across the British Isles regularly and they bring with them a fairly predictable pattern of weather. Meteorologists use synoptic charts or weather maps to help them to plot the movement of weather systems. Synoptic charts have isobars on them: lines which join points of equal pressure. The tighter the isobars are together, the faster the wind will be! Synoptic chart and satellite image of the lowest pressure ever recorded. On a synoptic chart, a depression appears as ‘sharks fin’ shape. The warm front is the leading edge of the warm air. The cold front is the leading edge of the cooler air. The cold front moves fast and lifts the warm air off the ground (known as an occlusion) The whole system moves across the UK from west to East. B A 14 A= E= Y6 Weather III Brambletye Geography Department Glossary Term Definition 15 Y6 Weather III Brambletye Geography Department Term Definition 16 Y6 Weather III Brambletye Geography Department Windy Wordsearch There are 25 words or phrases hidden in the grid below. Find them and make sure that they are in your glossary with a suitable definition. 17