weather [fronts] [appearing pictures]

• 1. weather map showing isobars fronts pressures wind speed/direction
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• 2. warm front [1] warmer air colder air front colour shape
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• 3. warm air rising [animation] change of temperature
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• 4. occluded front [1] [animation] showing warm air being trapped by cold air
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• 5. weather map [low pressure] [animation] radar of movement across USA
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• 6. jet stream [1] showing 2 streams one warm one cold
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• 8. jet stream [3] [animation] showing how jet stream blocks warm air
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• 9. jet stream [4] [animation] showing 24 hours
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• 10. jet stream [5] [animation] showing jet streams blocking warmer air
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• 11. showing high and low pressure areas either side of UK
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• 12. cold front [1] [animation] cold front pushing warm front Australia
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• 13. warm front [2] [animation] warm front pushing cold front UK
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• 14. weather front showing cloud names
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• 15. weather map [low pressure] [animation] radar of movement across USA
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• 16. cold front [3] cold front pushing against warm front
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• 17. cold front [4] [animation]
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• 18. cold front [5] colder air front warmer air
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• 19. air pressure [high and low] cold air warm air
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• 20. low air pressure [cold air]
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• 21. high air pressure [warm air]
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• 22. air masses [UK] [1] simply named
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• 23. air masses [UK] [2]
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• 24. air masses [UK] [3]
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• 25. air masses [UK] [4] simply named and directed
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• 26. air masses [UK] [5]
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• 27. air currents [sea breeze] [animation]
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• 28. air circulation [animation]
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• 29. warm air forced to rise over cold [animation] [1]
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• 32. convection rainfall [animation]
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• 33. 3D model of a front
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• 34. cold front [6] simple blue diagram
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• 35. warm front [4] simple red diagram
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• 36. occluded front [2] simple purple diagram
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• 37. stationary front [1] simple red and blue diagram
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• 38. cold front [7] [explanation]
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• 39. warm front [5] [explanation]
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• 40. occluded front [3] [explanation]
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• 41. stationary front [2] [explanation]
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• 42. cold front [8] [labelled]
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• 43. warm front [6] labelled]
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• 44. occluded front [4] [labelled]
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• 45. stationary front [3] [labelled]
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• 46. all fronts recap [labelled]
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• 47. cold front [9] [unlabelled]
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• 48. warm front [7] [unlabelled]
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• 49. occluded front [4] [unlabelled]
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• 50. stationary front [3] [unlabelled]
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• 51. cold front [10] [labelled]
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• 52. cold front [11] [unlabelled]
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• 53. front
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• 54. air circulation
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• 55. high and low pressure systems
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• 56. cyclones and anti-cyclones [1]
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• 57. cyclones and anti-cyclones [2] [part labelled]
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• 58. cyclones and anti-cyclones [3] [unlabelled]
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• 59. anti-cyclones [4]
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• 60. cyclones [5]
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• 61. high and low pressure systems [2] [labelled]
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• 62. high and low pressure systems [3] [unlabelled]
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• 63. high pressure systems [4] [unlabelled]
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• 64. low pressure systems [5] [unlabelled]
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• 65. high and low pressure systems [3]
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• 66. low pressure systems [4]
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• 67. high pressure systems [5]
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• 68. high and low pressure systems [4]
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• 69. high and low pressure systems [5] [unlabelled]
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• 70. low pressure systems [6] [labelled]
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• 71. high pressure systems [7] [labelled]
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• 72. high and low pressure systems [5] [labelled]
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• 73. high and low pressure systems [6] [labelled]
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• 74. low pressure systems [7] [labelled] converging winds
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• 75. high pressure systems [8] [labelled] diverging winds
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• 76. fronts [animation]
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• .
NOTES

1. Air masses are areas of air that bring distinctive weather features to the country.
2. An air mass is a body or 'mass' of air that have very little change temperature and humidity within them.
3. That is to say the air making up the mass is very uniform in temperature and humidity.
4. An air mass is separated from another body of air by a weather front.
5. An air mass may cover several millions of square kilometres and extend vertically throughout the troposphere.
6. High pressure (or anticyclone)
7. In an anticyclone (also referred to as a 'high') the winds tend to be light and blow in a clockwise direction.
8. Also the air is descending, which stops the formation of clouds.
9. The light winds and clear skies can lead to overnight fog or frost.
10. If an anticyclone persists over northern Europe in winter, then much of
the British Isles can be affected by very cold east winds from Siberia
11. However, in summer an anticyclone in the vicinity of the British Isles
often brings fine, warm weather.
12. Low pressure (or depression)
13. In a depression (also referred to as a 'low'), air is rising.
14. As it rises and cools, water vapour condenses to form clouds .
and perhaps precipitation.
15. Consequently, the weather in a depression is often cloudy, wet and windy
(with winds blowing in an anticlockwise direction around the depression).
16. There are usually frontal systems associated with depressions
17. Weather fronts
18. A weather front is simply the boundary between two air masses
19.There are three different types of weather front
20. 1. Cold front
21. This is the boundary between warm air and cold air and is where cold air
is replacing warm air at a point on the Earth's surface
22. On a weather chart) a cold front is a blue line with blue triangles on it
23. The presence of a cold front means cold air is moving in and pushing
underneath warmer air.
24. This is because the cold air is 'heavier' or denser, than the warmer air .
so sinks below it.
25. So cold air is replacing warm air at the surface.
26. Triangles on the front point to the direction that the front is moving.
27. You can tell when a cold front has passed by a rise of pressure, a fall of
temperature and dew point, and a change in wind direction.
28. Rain occurs with most cold fronts and may extend some 100 to 200 km
ahead of or behind the front.
29. Some cold fronts give only a shower at the front, while others give no
precipitation
30. Thunder may occur at a cold front.
31. Warm front
32. This is the boundary between cold air and warm air and is when warm air .
replaces cold air at a point on the Earth's surface.
33. On a synoptic chart a warm front is a red line with red semi-circles.
34. The presence of a warm front means warm air is moving in and rising up
over cold air.
35. This is because the warm air is 'lighter' [less dense]
than the colder air.
36. So warm air is replacing cold air at the surface
37. Semi-circles on the front point to which direction the front is moving
39.As a warm front approaches, temperature and dew-point within the
cold air gradually rise and pressure falls more quickly.
40. Precipitation usually occurs in a wide belt about 400 km just ahead
of the front.
41. When the front has passed, the will be a steadying of the barometer
(pressure will stop falling), a jump in temperature and dew point, a change
of wind direction, and precipitation will stop, or mostly stop
42. Occluded front
43. These are more complex than cold or warm fronts.
44. An occlusion is formed when a cold front catches up with a warm front.
45. When a cold front catches up with a warm front, the warm air
in the warm sector is forced up from the surface
46. On a synoptic chart an occluded front is a purple line
with purple semi-circles and triangles.
47. Not all occlusions follow the same rules, as some will be more similar to
warm fronts and some will be more like cold fronts, so some will cause it to
feel warmer once it has passed, others cooler, some will lower the dew
others will cause it to increase.
48. All occlusions will cause a rise in pressure, a change in wind direction
and precipitation will slowly clear when they have passed
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Read each of the labels. They explain what each of the linked pictures are showing. As you hover over each of the labels pictures will appear to help you better understand the topic.