Idea 2: Complete and retell it
The age old ‘fill in the gaps’ exercise with a little extra. Ideal if you are short on time or if you wish to set this as a homework task.
Starter
Put the class in pairs; one pupil represents High-pressure, the other Low-pressure. Set either a class agreed or pre-agreed criteria on what should be included on the board. Pupils then create a representation of High and / or Low-pressure. This can be in any format they wish as long as it covers the pre-agreed criteria. Pupils then present their creation to their partner which can then be peer assessed using the criteria.
Main
1. Play the on the GAC. Pupils watch it once without filling in anything.
2. Once the video has finished, pupils can fill in any gaps they feel confident about on the sheet created using the text below.
3. Play the video for the second time. This time, pupils can fill in the gaps they have missed.
4. Project the answers on the board to self-assess once finished.
5. Class discussion to support with any misconceptions plus challenge those who are confident.
6. Summarise the text in a series of annotated diagrams at the bottom of the page.
GAC video summary
Below is the summary of the video. Feel free to remove specific words for your class for their gap fill task.
As some parts of our planet is slanting towards and others away from the Sun, the Sun’s energy has different effects on the planet. In places that experience high Sun intensity, such as in the Tropics, the focus is strong and therefore hotter. Other parts which have lower sun intensity, the energy is spread out meaning there is more variation in the heat that area receives.
The Earth warms the air above it, causing it to rise. If the planet did not rotate, then there would just be one cell: hot air rising from the Tropics spreading north and south eventually cooling and sinking in the Polar regions then coming back towards the tropics in one complete convection cell.
However, as the planet rotates, it influences the movement of air. The Equator has the largest circumference (40,075 km). Around this part and into the tropics, the air moves quickly. However, as the Poles are effectively spinning on the spot, air barely moves.
The air from the Tropics to the Poles and from the Poles back to the Tropics is moving in a straight line but it is at a different speed in relation to the Earth, therefore, it appears to move east to west (easterlies) or west to east (westerlies). This is called the Coriolis Effect.
Because of the Coriolis Effect, the single cell is disrupted and therefore, the planet has three main cells: the Hadley, Ferrell, and Polar Cells. These are repeated on either side of the Equator in the Northern and Southern Hemispheres.
The Hadley Cell starts at the Tropics where heat from the Sun’s energy causes warm air to rise moving outwards towards the Polar regions. Warm air moves from the Tropics becoming more westerly as it gets deflected by the Coriolis Effect. So much so that eventually, the cell breaks down and air sinks at the sub-tropics (30o N or S of the Equator) and returns to the Tropics. This air moves more slowly over ground which, in relation to the air is moving faster making them look like they are moving from east to west (easterlies).
The same pattern happens in the Polar regions at the Polar Cell (60o N or S of the Equator). However, the differences are that this cell is driven by sinking cold air and generates slow moving polar air.
The Ferrel Cell behaves slightly differently to the Polar and Hadley Cells and is the net effect of all storms in the mid-latitudes with air sinking in sub-tropics and rising 50-70o N or S of the Equator. This air moves west to east (Westerlies). The air is pulled across the surface towards the Poles and picks up moisture along the way. When warmer, moisture ridden air meets colder air from the Polar regions, it rises, cools and condenses creating unsettled weather which is regularly experienced in the UK.
Plenary
Pupils work in pairs to retell how the GAC works using their diagrams only.