weather [appearing pictures with notes] [2]

• Let's recap what we have covered in weather [1]............
• Air masses are bodies of air. Here is a cold air mass and a warm air mass over Australia.
• In the UK we are influenced by cold northern air masses.........
• .......and two warm southern air masses.. This is why our weather is so mixed.
• The lines on this UK map are called isobars. They mark areas of same air pressure.
• Here you can see them without the map. A high pressure area and a low pressure area.
• High pressure areas move towards low pressure areas which causes a weather front.
• A weather front is where warmer air and cooler air meet.
• The weather front is marked where the two air pressure systems meet, in blue and red.
• This animation shows a front moving across the USA causing rainfall behind it.
• There are four different types of weather front, the first is a cold front.
• This is what it looks like on a weather map, a line with blue triangles.
• The second is a warm front.
• This is what it looks like on a weather map, a line with red semicircles [mass] not ass.
• The third is an occluded front.
• This is what it looks like on a weather map, a line with blue triangles and semicircles.
• The fourth is a stationary front.
• This is what it looks like on a weather map, a line with blue triangles and red semicircles.
• Weather fronts are the boundaries between high and low pressure areas.
• This animation shows the movement of a warm front across the southern half of the UK.
• Let's recap what we have covered............

Read each of the labels in turn. As you hover over each of the labels a picture will appear to help you better understand what the label is saying and explaining what the words in bold mean.