Wave effect

78 views
Skip to first unread message

xmetman

unread,
Jun 18, 2018, 3:44:03 AM6/18/18
to weathera...@googlegroups.com

The wave effect seems to be in the SC layer at around 4000 to 5000 feet.

Before you ask - I've ovelaid the IR image and added som false colour to it to pick up the medium and high level cloud. The cirrus of Angus could be orographic from the flow over the Grampians.


Jack Harrison

unread,
Jun 18, 2018, 4:01:32 AM6/18/18
to Weather and Climate

Gliding hat on


There is a common misconception that mountain wave cloud always classic lenticular..  Not always so.  In my own gliding experience (my greatest height 27,000 feet+) the strongest and highest wave is above what looks like stratocu at around 3 – 5,000 feet (as today).   I did much but not all my wave flying  from Aboyne in the Dee Valley.


Current Aboyne webcams.  The bottom image is the most useful - faces west up the valley.

http://www.deesideglidingclub.co.uk/webcam.html


When they get out of bed, you might be able to follow the gliders here:

http://live.glidernet.org/#c=56.78335,-2.37791&z=8&p=3&u=i


Jack

Jack Harrison

unread,
Jun 18, 2018, 5:56:41 AM6/18/18
to Weather and Climate
shows well how they are standing waves.

Jack

xmetman

unread,
Jun 18, 2018, 6:31:54 AM6/18/18
to Weather and Climate
There looks like a wave to that cirrus...

Len W

unread,
Jun 18, 2018, 11:56:12 AM6/18/18
to Weather and Climate
All orographic induced waves are standing waves. Whether they are lenticular or not.
They are tied to the orography, unlike billow clouds induced just by wind shear across a stratocu or altocu sheet.

Len
Wembury

xmetman

unread,
Jun 18, 2018, 12:03:09 PM6/18/18
to Weather and Climate


Jack Harrison

unread,
Jun 18, 2018, 1:08:24 PM6/18/18
to Weather and Climate

When gliding from Aboyne in a westerly or south westerly, the “hot spot” for contacting wave is as illustrated.  Now the line of “lift” is usually over that road or at least, following the alignment of that road.  But in stronger winds (or different vertical temperature profile), the actual line might be displaced downwind (paler blue dots).

Pilots can be caught in the wrong place because they haven’t appreciated that the wave has shifted either downwind or upwind of the usual spot.  So it is only partially true to say that:

“All orographic induced waves are standing waves.”  The wind and temperature profiles don’t usually change abruptly but that can happen.  So it is occasionally possible to get moving (jumping) rather than standing orographic wave.


Jack

Freddie

unread,
Jun 19, 2018, 5:57:56 AM6/19/18
to Weather and Climate


On Monday, 18 June 2018 18:08:24 UTC+1, Jack Harrison wrote:
Pilots can be caught in the wrong place because they haven’t appreciated that the wave has shifted either downwind or upwind of the usual spot.  So it is only partially true to say that:

“All orographic induced waves are standing waves.”  The wind and temperature profiles don’t usually change abruptly but that can happen.  So it is occasionally possible to get moving (jumping) rather than standing orographic wave.


Isn't it true to say that it is still a standing wave, but has moved to "stand" in a different position because of wind or stability changes?

--
Freddie
Ystrad
Rhondda
148m AMSL
http://www.hosiene.co.uk/weather/
https://twitter.com/YstradRhonddaWx for hourly reports (no wind measurement currently)
Reply all
Reply to author
Forward
0 new messages