STANDARD GADE GEOGRAPHY Lesley Monk Balfron High School
STANDARD GADE GEOGRAPHY Lesley Monk Balfron High School Session 2005. 6 WEATHER
STANDARD GRADE GEOGRAPHY WEATHER SYSTEMS Read the textbook page 27, section 4 A. (Note that air streams are sometimes also called air masses. ) WEATHER
STANDARD GRADE GEOGRAPHY WEATHER The air streams for the UK can also be labelled with more technical terms; Continental streams are from a large land mass like Europe or Africa. Maritime ones are from a large ocean like the Atlantic or Arctic Tropical ones originate in warmer areas like North Africa or Caribbean Polar streams start in very cold areas like Siberia or the Arctic Most air streams are named using TWO letters; Ct, Cp, Mt, Mp
STANDARD GRADE GEOGRAPHY 8 WEATHER On your copy of the map in figure 4. 1 A, Page 27, add the missing labels. If you can, add in a small circle next to each arrow, the TWO letters that ‘name’ the stream. Ct example Note that there is usually a difference between winter and summer in the weather brought by air streams.
STANDARD GRADE GEOGRAPHY AIR PRESSURE SYSTEMS There are two main types of air pressure systems. HIGH pressure is when air is heavy and is pressing down on the surface. LOW pressure is when air is light and rises up into the upper atmosphere. WEATHER Can you remember the name of the instrument to measure this element? What unit does it use?
STANDARD GRADE GEOGRAPHY Warm air rising causes LOW pressure. WEATHER Use colour! Cold air falling causes HIGH pressure. wind The Earth’s surface is warmed by the sun’s rays.
STANDARD GRADE GEOGRAPHY I like to think of the two pressure types as being like Gods’ power hose and His vacuum cleaner ! WEATHER hose HIGH LOW WIND Winds flow to Low pressure from High pressure
STANDARD GRADE GEOGRAPHY WEATHER PROPER NAMES; Low pressure systems are called DEPRESSIONS or CYCLONES. They spin in an anti- clockwise direction. Low High pressure systems are called ANTICYCLONES and they spin slowly in a clockwise direction. Each of these systems brings different weather- more later!
STANDARD GRADE GEOGRAPHY WEATHER When air pressure is plotted onto a map, lines of equal pressure are drawn; these are called ISOBARS, and are very important. From the patterns that emerge, centres of high and low pressure can be identified. (Isobars are like the contour lines of the air. ) Can you read how far apart these isobars are, in millibars?
STANDARD GRADE GEOGRAPHY 9 WEATHER Fill in the missing items into your copy.
STANDARD GRADE GEOGRAPHY WEATHER DEPRESSIONS CLOSE-UP Read page 27, section 4 B of the textbook. Look at figure 4. 2 on the next page. Imagine the air passing over the ground from west to east. As the system passes overhead, the people on the ground will experience the weather changes. Now read section 4 D- we will return to read 4 C later. You will need to be able to describe and explain the changes in the weather as experienced by people on the ground as the system passed over them.
STANDARD GRADE GEOGRAPHY WEATHER This is a satellite photograph of a depression. Note the swirling pattern of white clouds that show the fronts. The dark is the sea below the system.
STANDARD GRADE GEOGRAPHY Now carefully make your own copy of the two diagrams in the textbookfigure 4. 2 with all labels. Lay them out as in the book, one exactly above the other. Use the same colours as well. Label the top one ‘ air direction in a depression’ and the lower one ‘ cloud formation in a depression’. Copy section 4 D from page 28, then figure 4. 4 on page 29. WEATHER
STANDARD GRADE GEOGRAPHY THE WARM FRONT CUMULUS clouds bring prolonged rain at the warm front m War t Fron WEATHER CIRRUS are very high and wispy. They are usually the first clouds we see as the warm front approaches Dense cool air
STANDARD GRADE GEOGRAPHY WEATHER WHAT HAPPENS AT THE WARM FRONT? Warm air begins to rise over the cooler air. As this air rises, it begins to cool. Cool air can hold less water vapour than warm air Water vapour begins to condense into water droplets. Water droplets begin to form clouds. The first – and highest – type of cloud to form along the warm front is called Cirrus
STANDARD GRADE GEOGRAPHY WEATHER AN APPROACHING WARM FRONT CIRRUS STRATUS CUMULUS
STANDARD GRADE GEOGRAPHY WEATHER WHAT HAPPENS AT THE COLD FRONT? The cold Arctic air moves faster than the warm air. The cold Arctic air is denser than the warm air. The cold Arctic air undercuts the warm air, forcing it up. Water vapour begins to condense into water droplets Water droplets begin to form very tall clouds The clouds along the cold front are called Cumulonimbus.
STANDARD GRADE GEOGRAPHY WEATHER Very tall clouds are formed by the rapidly rising air. These are called CUMULONIMBUS give very heavy showers, sometimes with thunder and lightning. The Warm Sector (warm, moist air) PRECIPITATION AT THE COLD FRONT
STANDARD GRADE GEOGRAPHY Click on the red labels find out more! WEATHER
STANDARD GRADE GEOGRAPHY WEATHER
STANDARD GRADE GEOGRAPHY WEATHER Answer these questions about depressions, in sentences. 1. Why do clouds only form around fronts? 2. Which front is always the first over an area? 3. Describe the sort of angle it makes with the ground. 4. What kind of air lies between the fronts? 5. Describe the angle the second front makes with the ground. 6. What is the result of this different angle? 7. Which front has the longest ‘raining time’? 8. Which front has the heaviest rainfall?
STANDARD GRADE GEOGRAPHY WEATHER t n o r f ir m What happens next in a a r d ol e wa arm c depression? he h th e w t h y t t l i l a p w all u t en es u hing v E ch s. Th u t p y a t, e a c w are tw n a o r o f and FR cal fro l up set ONT ed a nts t tim s of and n OC oget erai we CLU her ugh n a ge DE t t ! the bot D sam h Occluded front e symbol
STANDARD GRADE GEOGRAPHY WEATHER ANTICYCLONES Read section 4 E on page 28. Note that fronts are not part of a high pressure system! Remind yourself about the sort of weather in an anticyclone- handout 9. This is a picture of typical winter high pressure weather. Note the calm conditions and fog!
STANDARD GRADE GEOGRAPHY WEATHER This handout is about wind direction and speeds in high and low pressure areas. 11 Exam-type questions; These are usually in one of two forms. One asks you what the weather is like at place X on the chart, either now or later. The other asks you to choose the best set of station circle symbols to show the weather a place is getting. 12 With both, you will need to give reasons for your answers. Try the questions on handout 12.
STANDARD GRADE GEOGRAPHY WEATHER This handout is about wind direction and speeds in high and low pressure areas. 11 Exam-type questions; These are usually in one of two forms. One asks you what the weather is like at place X on the chart, either now or later. The other asks you to choose the best set of station circle symbols to show the weather a place is getting. 12 With both, you will need to give reasons for your answers. Try the questions on handout 12.
STANDARD GRADE GEOGRAPHY QUICK TEST TIME! WEATHER YOU MAY BE GIVEN SOME OR ALL TO DO AS HOMEWORK! If so, do it on paper, not in your jotters. 1. Everyone should do the CORE ( blue) questions on page 30 of the textbook. 2. Then you can choose to do any mixture of FOUNDATION, GENERAL CREDIT or EXTENSION questions. Do a total of six questions.
STANDARD GRADE GEOGRAPHY CLOUD PRECIPITATION TEMPERATURE WIND DIRECTION AIR PRESSURE WEATHER
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