References: -A-CR-CCP-242/PT-005 Chapter 2 -Transport Canada Study and Reference Guide Glider Pilot - -FTGU pages 135-138, 146-147 : Instructor 40 Minutes 5.03 Moisture BC Online Ground School: Meteorology References: -A-CR-CCP-242/PT-005 Chapter 2 -Transport Canada Study and Reference Guide Glider Pilot - -FTGU pages 135-138, 146-147
Slide 2 : MTPs:
Relative Humidity and Dew Point
Changes of State
Cloud Formation
Precipitation
ICAO Lapse Rates
Slide 3 : Relative Humidity
Ratio of water present in air compared to the amount the same volume could hold if it were saturated
Dew Point
Temperature to which air must be cooled at constant pressure to become saturated
Slide 4 : The warmer the air, the more water vapour it can hold...Why? 1 kg air at 0 degrees
= 5g water 1 kg air at30 degrees
= 30g water
Example : Example If we took a parcel of air at 10oC at 100% relative humidity and warmed it up, how would the relative humidity change?
Slide 6 : Questions:
1. Define Relative Humidity.
The ratio of water present in the air compared to the amount the same volume could hold if it were saturated
2. Define Dew Point
Temperature to which air must be cooled at constant pressure to become saturated
Slide 7 : Freezing
Evaporation
Melting
Sublimation
Condensation
Slide 8 : GAS LIQUID SOLID ICE WATER VAPOUR WATER Freezing Melting Evaporation Condensation Sublimation Sublimation
Slide 9 : Questions:
1. What do you call a change of state from liquid to solid?
Freezing
2. From solid to gas?
Sublimation
3. From vapour to liquid?
Condensation
Cloud Formation : Cloud Formation
Slide 11 : Invisible water vapour becomes visible as water droplets or ice
Condensation of water vapour
Slide 12 : What is required:
High relative humidity
Condensation nuclei
Cooling of the air
Cold surface
Adiabatic cooling
Slide 13 : Steps Air is heated and rises
Air cools to point of saturation
Air condenses onto condensation nuclei
Slide 14 : Question
What are the three things required for cloud formation?
High relative humidity
condensation nuclei
cooling of the air
Precipitation : Precipitation
Slide 16 : Water droplets grow in size and weight and fall due to gravity
Can also occur below freezing (water vapour and ice crystals) The average rain drop is a million times larger than a cloud water droplet
Slide 17 : If the cloud is…..
Below freezing – joining of ice crystals
Above freezing = rain
If temp below is cold enough to allow crystals to fall to ground = snow
Slide 18 : Regions of a cloud Snow Rain and/or snow Rain Large drops and heavy rain = strong vertical motion
Slide 19 : Types of precipitation
Drizzle
very small drops of water which appears to float
Rain
Large water droplets
Slide 20 : Hail
Hard transparent layer of ice covering soft white core
Snow Grains
Tiny snow crystals that have acquired a coating of rime
Slide 21 : Snow Pellets
Soft white ice (hail without hard transparent layer
Snow
Agglomeration of ice crystals hexagonal/star shaped
Slide 22 : Ice Prisms
Tiny ice crystals in the form of needles
Ice Pellets
Formed by freezing of raindrops MTP: Precipitation
Slide 23 : Question
What are the 8 different types or precipitation?
Slide 24 : Lapse rate
Rate of decrease in temperature with altitude
Slide 25 : Lapse rates:
Recall ICAO Standard Atmosphere:
Air is perfectly dry gas
Mean sea level pressure of 29.92
Mean sea level temp of 15°C
Slide 26 : Can determine base of clouds:
Temperature on ground 10 degrees
Dew point 7 degrees
Lapse Rate Saturated adiabatic (1.5/1000 ft)
Cloud base = 2000 feet
Slide 27 : Inversion
Increase in temperature with altitude
Isothermal Layer
Layer in which temperature remains the same
Slide 28 : Confirmation
1. What is the dry adiabatic lapse rate?
_____ degrees per _________feet
2. What is hail?
Hard transparent layer of ice covering soft white core
3. A parcel of air has a relative humidity of 50%. If the temperature were to decrease how would the relative humidity change?