1. Meteorology – Jet Streams Fronts and Air Masses Connecting the Weather Air Masses Fronts Jet Stream Quiz Midweek Seminars

2. Meteorology – Jet Streams Fronts and Air Masses Air Masses A mass of air takes on Temperature and Moisture from where the source of air originates. Source Region - Land or Sea Amount of Time over the Source region Modification as the Air Mass moves away from the source. Midweek Seminars

3. Meteorology – Jet Streams Fronts and Air Masses Air Mass Classification and humidity Artic – Polar Ice Cap in Winter Polar – Forms 40’ to 60’, Summer up to 80’ Tropical – Forms from high pressure cells, Summer over large continents Equatorial – Region between Sub tropical Highs Humidity depends on source Maritime – Forms over Water – more humid Continental – Originates over Land – less humid Midweek Seminars

4. Meteorology – Jet Streams Fronts and Air Masses Midweek Seminars Air masses affecting the UK are either Polar or Tropical with Artic air mass in winter

5. Meteorology – Jet Streams Fronts and Air Masses What happens as an Air Mass moves from Cold to Warm? Air becomes heated in the Lower Levels To pilot this gives you.. Unstable Air Warmer Air Low Humidity Midweek Seminars What happens as an Air Mass moves from Warm to Cold? To pilot this gives you.. More stable air Colder in lower levels Increased Humidity

6. Meteorology – Jet Streams Fronts and Air Masses Air Masses Polar Maritime Source – Greenland & Iceland Conditions at Source Cold Stable High Humidity As Air Mass moves South East becomes Unstable resulting in Cu and Cb over Land Heavy Showers, Rain, Hail Moderate to severe Icing Good Visibility Midweek Seminars

7. Meteorology – Jet Streams Fronts and Air Masses Air Masses Tropical Maritime Source – Azores Conditions at Source Warm Slight Instability Moderate Humidity As Air Mass moves North East Air cools from below Advection Fog St & Sc by day St at night Poor Visibility Midweek Seminars

8. Meteorology – Jet Streams Fronts and Air Masses Air Masses – Tropical continental Source – North Africa Conditions at Source Warm Stable Low Humidity As Air Mass moves North it cools from below becomes more stable, Humidity stays low. Hot & Dry weather Poor Visibility due to Haze Midweek Seminars

9. Meteorology – Jet Streams Fronts and Air Masses Air masses, Arctic Maritime, Winter only Source – Artic Circle Conditions at Source Cold Stable Low Humidity As Air Mass moves South it is heated from below becomes VERY unstable, Cold Moist - Precipitation Heavy Snow Cu & Cb Clouds Unstable Possible Thunderstorms Midweek Seminars

10. Meteorology – Jet Streams Fronts and Air Masses Air Masses, Polar continental, Winter only Source – Siberia & North Europe Conditions at Source Cold Stable Low Humidity As Air Mass moves over cold land of Europe it stays cold and stable Cold Very Dry No Precipitation Possible Thunderstorms along east coast if Air Mass has moved over North Sea Midweek Seminars

11. Meteorology – Jet Streams Fronts and Air Masses Midweek Seminars

12. Meteorology – Jet Streams Fronts and Air Masses Midweek Seminars Coffee!!!!!

13. Meteorology – Jet Streams Fronts and Air Masses When Air Masses meet we call them… Fronts A front is a zone of transition between two contrasting air masses The three types of front are Cold Warm Occluded The interaction of two air masses at the frontal surface frequently gives rise to a great deal of frontal cloud and weather. Midweek Seminars

14. Meteorology – Jet Streams Fronts and Air Masses Fronts Typical cross section through a frontal system Midweek Seminars

15. Meteorology – Jet Streams Fronts and Air Masses Warm front Midweek Seminars

16. Meteorology – Jet Streams Fronts and Air Masses Warm Front Weather Midweek Seminars Wind veers & increases slightly Temperature / Dewpoint rise. Pressure steadies Precipitation changes from RA to DZ or DZRA. Cloud changes from NS to ST or SC.

17. Meteorology – Jet Streams Fronts and Air Masses Cold Front Midweek Seminars

18. Meteorology – Jet Streams Fronts and Air Masses Cold Front Weather Midweek Seminars Pressure rises rapidly Wind veers and decreases slightly Temp / Dew point fall. Visibility improves Intermittent Rain Heavy Showers begin from NS / Embd Cb

19. Meteorology – Jet Streams Fronts and Air Masses Midweek Seminars

20. Meteorology – Jet Streams Fronts and Air Masses Warm Occlusion Air Masses Fronts Jet Stream Quiz Midweek Seminars Less cold air over-rides colder air ahead.

21. Meteorology – Jet Streams Fronts and Air Masses Cold Occlusion Midweek Seminars Colder air under-cuts less cold air ahead

22. Meteorology – Jet Streams Fronts and Air Masses Midweek Seminars

23. Meteorology – Jet Streams Fronts and Air Masses Jet Streams Midweek Seminars A jet stream is an river of high velocity air with velocities of 60 – 250kt, on rare occasions 300kt flowing generally west to east It is a wind belt in created by thermal wind in a boundary zone between warm and cooler air i.e. a frontal zone. It usually separates the colder and warmer air.

24. Meteorology – Jet Streams Fronts and Air Masses Jet Streams Max wind speed in a Jet Stream is found on the warm side of the frontal zone at an altitude just above than of the cold tropopause and below that of the warm tropopause and the direction usually agrees with that of the front. Midweek Seminars

25. Meteorology – Jet Streams Fronts and Air Masses Connecting the Weather Interpretation of Wx info Tips for en route Wx interpretation and cross referencing Met charts Example: F215 shows vis 999 ocnl SHRA 4km vbis cloud 2500 ocnl 1500 METAR 9999 BKN 2500 SHRA ; TAF 9999 BKN 2500 PROB30 TEMPO 5000 +SHRA AIRMET Says cold front with gusting winds passing early in day, isolated heavy showers later Conclusion, flight can go ahead, choose alternate carefully and proceed with caution. Midweek Seminars

26. Meteorology – Jet Streams Fronts and Air Masses Quiz Define CAVOK More than 10k vis, no cloud below 5000ft or MSA, no CuNim in vicinity SHSNRA VV003 Heavy showers of snow or rain, vertical visibility 300ft An airmet says Cold Sector. Conditions? Colder dryer air, good vis, scattered cumulus METAR : EGLF 031450Z 02012KT 6000 BKN017 04/00 Q1034. Flyable? Yes METAR : EGLF 031450Z 02012KT 9000 OVC005 04/04 Q1004. Flyable? No TAF says PROB30 TSRA BKN 020 flyable? Yes with caution PROB50 Exists? No, any more than PROB40 is BCMG or TEMPO Midweek Seminars Met Office website Form 214-215 TAFs, METARs, AIRMET Other sites, XCweather.co.uk, avbrief.co.uk, sky demon

27. Meteorology – Why it’s a bad idea to bypass proper Met planning Midweek Seminars