High Flight (Courtesy Richard de Crespigny)

Only those who fly fully appreciate the wonders that exist out the front of  the cockpit.  Our passion is fueled by the experiences of seeing and feeling many things, including the extraordinary cloud types that comprise our living atmosphere.

My memories of clouds include the theory in the RAAF’s class rooms, tempered and case hardened by experiences in the cockpit:

• Memories of  “feeling our way” through thunderstorms in the RAAF Caribous (we had no radar to see them), ensuring that we disconnected the High Frequency (HF) radio antennae before a lightning strike fused our radios;
• The experience of being semi out-of-control in updrafts and downdrafts whilst flying in the RAAF (hold on, maintain a normal attitude and wait till it clears);
• The experiences of crossing, or jumping on the back of Jet Streams (narrow bodies of air that form due to temperature shears that can travel up to 300 kilometers per hour);
• The threatening view of roll clouds in front of thunderstorms that took on the colour of their contents (green ocean water) ;
  

  Roll Cloud (Source: Wikipedia)

• The seemingly innocent and beautiful views of “virga”, rainfall that evaporates before descending to the ground, but acts as the cooling process to create dangerous micro-bursts that are deadly to aircraft near airports;
  

  Virga (Source: Wikipedia)

• The fascinating events during lightning strikes to aircraft;
• Morning Katabatic winds that roll down mountain slopes in Perth, Adelaide, Jordan and Los Angeles; and
• “Rotors” of turbulent air that form in the lee of the escarpment just a few miles to the east of Perth Airport in Western Australia.   Every Perth inhabitant who has flown has probably experienced this rough ride just prior to landing or after takeoff.

Thunderstorm bashing up against the tropopause as we crossed the ITCZ over the Pacific Ocean on 24 December 2012.

The above photo of a thunderstorm was taken during my  crossing of the Pacific Ocean on my way from Melbourne, Australia to Los Angeles, USA.   We departed LAX  on the 24th December and landed in Melbourne on the 26th, so we enjoyed Christmas Day in-flight, watching out for and ready to avoid an unlicensed sleigh.

We were flying through the Inter Tropic Convergence Zone (ITCZ), a corridor ringing the Earth that marks the most heated surface temperatures,  that trails the sun’s highest position in latitude by one month.    The warmer surface heats the air more than the surrounding cooler surfaces.

Convective forces lift moist air mass in the ITCZ to form the highest and most spectacular thunderstorms on the planet.

• The water vapour causes the wet rising air to cool slower than the surrounding drier ambient air.   This growing temperature difference causes the rising column to become even more buoyant in the atmosphere.  The buoyant thunderstorm clouds can often ascend at more than 5,000 feet per minute.
• The thunderstorm tops rise until the atmosphere becomes stable.  The highest stable altitude is found at a point called the Tropopause, where the air temperature remains constant as the altitude increases.  The tropopause can be located anywhere from 25,000 (poles) up to 60,000 (equator) feet above the surface.   Many ITCZ thunderstorms reach these amazing heights and then then “top out” at  after punching though the tropopause.  This is the reasons that the coldest atmospheric temperatures exist over the equator!

Another night flying at 40,000 feet avoiding spectacular and massive storm cells. In this case we are 44nm (81 km) left of track and heading 120 degrees away from our next waypoint! Activity increases as the colour changes from green, through yellow and red to magenta. Our TCAS system displays an equally cautious aircraft in our seven o’clock and 2,000 feet below. (Courtesy: Richard de Crespigny)

Every pilot who flies through the ITCZ knows about these dangers and avoids thunderstorms accordingly.  We are always on alert, aware that a “safe” radar picture one minute can change into a “dangerous” paint the next.  We never fully trust the radar presentations.

The pilots creed of “one look outside is worth 100 radar scans” holds true and at night.  Whilst the passengers are snug in their seats watching the latest video, we have turned down the cockpit lighting to the minimum and pressed our faces against the windows, using the “Mark 1 Eyeball” to scan the outside horizon for dangerous storm cells.

We were flying at 38,000 feet when I took the above picture of the ITCZ thunderstorm.  You can see the top of the thunderstorm flatten out as it punches through the tropopause, its inertia pushing and penetrating the tops up into the calm troposphere.   The rising air has lifted the bottom of the troposphere deforming the high, flat cirrus cloud to take on a “concave” or “Lenticular” type cloud form.

The energy in this thunderstorm, if tapped, would have powered a city for a day.

This is just another day in the life of an airline pilot.

Our 400 passengers were either asleep in the A380’s remarkably quiet cabin, or watching one of the thousand in-flight movies.  Whilst they relaxed with their window shutters closed, we dodged one ITCZ thunderstorm after another, banking and weaving, banking and weaving through the sky, all the time ensuring that the aircraft rolled at a rate less than three degrees per second – a rate that is undetectable to our passengers.    We were busy in the flight deck whilst the passengers presumed that their pilots were carving a straight line through clear skies.

Not a drop was spilled from any glass.

Below is an excellent photo taken by Witta Priester and displayed on NASA’s  apod.nasa.gov/apod website.   This Undulatus asperatus cloud shows features of lenticular activity  that appear to merge into a larger stratus layer.  The photo was taken in New Zealand, a country given the moniker “the land of the long white cloud” – another pointer to lenticular activities.  This photo supports my belief that New Zealand is one of the most majestic and beautiful mountainous (and maritime) countries in the world.

Asperatus Clouds Over New Zealand (Image Credit & Copyright: Witta Priester)

“High Flight”

by John Gillespie Magee, Jr. (9 June 1922 – 11 December 1941)

Every pilot’s delight. (Courtesy Richard de Crespigny)

Oh! I have slipped the surly bonds of Earth
And danced the skies on laughter-silvered wings;
Sunward I’ve climbed, and joined the tumbling mirth
Of sun-split clouds, — and done a hundred things
You have not dreamed of — wheeled and soared and swung
High in the sunlit silence.  Hov’ring there,
I’ve chased the shouting wind along, and flung
My eager craft through footless halls of air….
Up, up the long, delirious, burning blue
I’ve topped the wind-swept heights with easy grace,
Where never lark, or even eagle flew —
And, while with silent, lifting mind I’ve trod
The high untrespassed sanctity of space,
Put out my hand, and touched the face of God.