1. Uncontrolled copy not subject to amendment
Basic Navigation Using Map and Compass

2. Basic Navigation Using Map and Compass
Learning Outcome 5: Be able to recognise weather conditions that affect land navigation

3. Hot and Cold Air Masses BECAUSE OF THE RELATIONSHIP OF THE EARTH’S
UK SUMMER
AUSTRALIA WINTER.
AUSTRALIA SUMMER
UK WINTER.
BECAUSE OF THE RELATIONSHIP OF THE EARTH’S
ORBIT AROUND THE SUN TO THE TIME OF YEAR,
THE ANGLE THAT THE SUN’S RAYS HIT THE EARTH
VARY WITH TIME.

4. MOISTURE IN THE AIR
ALL AIR CONTAINS MOISTURE.
IT IS ONLY THE AMOUNT THAT VARIES.
HOW THE AIR ARRIVES AT OUR SHORES
AFFECTS THE MOISTURE IN THE AIR.
IF IT HAS TRAVELLED OVER LAND IT IS MOST
LIKELY TO BE DRY. LITTLE MOISTURE.
IF IT HAS TRAVELLED OVER THE SEA IT IS MOST
LIKELY TO BE WET. LOTS OF MOISTURE.

5. MOISTURE IN THE AIR
THE AMOUNT OF MOISTURE SUSPENDED IN THE AIR
IS DEPENDENT ON THE AIR TEMPERATURE.
THE WARMER THE AIR THE MORE MOISTURE IT WILL
HOLD.
THE MOISTURE CANNOT BE SEEN UNTIL THE AIR
BECOMES SATURATED AND THE MOISTURE COMES
OUT OF SUSPENSION AND FORMS CLOUDS.
THE SATURATION POINT IS KNOWN AS THE ‘DEW POINT’.
THE TYPE OF CLOUD FORMED IS DEPENDENT ON THE
RATE OF TEMPERATURE CHANGE AND THE STRENGTH
OF THE WIND.

6. Width of the arrows indicates the frequency of occurrence
Main Air Masses
Width of the arrows indicates the frequency of occurrence

7. Main Air Masses ARCTIC MARITIME – VERY COLD AND WET/SNOW
POLAR MARITIME – COLD AND WET/SNOW
RETURNING POLAR MARITIME – COOL AND WET
TROPICAL MARITIME – WARM AND WET (GULF STREAM)
TROPICAL CONTINENTAL - HOT AND DRY
POLAR CONTINENTAL – COLD AND DRY IN WINTER
WARM AND DRY IN SUMMER

8. ICAO STANDARD ATMOSPHERE
BASED ON SEA LEVEL
ACCEPTED AROUND THE WORLD
PRESSURE Mb
TEMPERATURE 15º C
LAPSE RATE OF -1.98ºC/1000Ft

9. Weather Map WIND CIRCULATES ANTI-CLOCKWISE AROUND A ‘LOW’.
AND CLOCKWISE
AROUND A ‘HIGH’.

10. Fronts and Frontal Depressions
Numbers refer to pressure in millibars

11. Weather Map – Westerly Winds

12. Depression Chart

13. Depression

14. Fronts and Frontal Depressions
Section through a frontal system
Cold front is steeper than the warm front

15. High and Low Pressure

16. High and Low Pressure

17. Upper Winds Weather map showing isobars for both upper
and lower winds.
Lower winds affect
the weather we get.
Upper winds affect
the speed the weather
system moves.

18. SURFCE PRESSURE CHART – NORTH ATLANTIC & EUROPE

20. Names For Clouds The names for clouds are usually combinations of the
following prefixes or suffixes:
Stratus/strato = flat/layered and smooth
Cumulus/cumulo = heaped up/puffy, like cauliflower
Cirrus/cirro = High up/wispy
Alto = Medium level
Nimbus/Nimbo = Rain-bearing cloud

21. CLOUD LEVELS HIGH CLOUDS BASE USUALLY 20,000ft OR ABOVE OVER UK.
TYPES – CIRRUS
CIRROCUMULUS
CIROSTRATUS
MEDIUM CLOUDS
BASE USUALLY BETWEEN
6,500ft AND 20,000ft OVER UK.
TYPES – ALTO CUMULUS
ALTO STRATUS
NIMBOSTRATUS
LOW CLOUDS
BASE USUALLY BELOW
6,500ft OVER UK.
TYPES – STRATO CUMULUS
STRATUS
CUMULUS
CUMULONIMBUS

25. Approaching Rain

26. Warm Front

27. Cold Front

28. Occluded Front

29. Depression Cross Section Cloud Type

30. Depression Cross Section Air movement

31. TYPES OF CLOUD

32. TYPES OF CLOUD

33. TYPES OF CLOUD

34. TYPES OF CLOUD

35. TYPES OF CLOUD

36. CUMULONIMBUS CLOUD TYPICAL ANVIL HEAD TO THE CLOUD
AS THE RISING AIR COMES TO A STOP
AND THE UPPER WINDS PULL THE
TOP CLOUD OFF THE COLUMN.

37. Local Warming

38. Pockets of Air

39. Thermals above

40. Air rising over mountains

41. Rising Air Dewpoint

42. Cloudy foothills

43. Funnels and Eddies

44. Banner Clouds

45. Temperature Inversion

47. stratus
cumulonimbus
cumulus
stratocumulus

55. Matches pressure chart

56. TYPES OF CLOUD

57. TYPES OF CLOUD