May 05, 2012, 08:51 AM sewing machine thumb United States, CA, Palo Alto Joined Jul 2001 2,305 Posts Discussion Third vector says thermal is thataway, but how far? I'm hoping that I learned a bit about air reading at the IHLGF last weekend. I've been reviewing JW's third vector diagram, and trying to put it into practice, but now I'm hung up on the question of how far to look for a thermal once I've gotten an idea of what direction to search. I assume the velocity of the thermal inflow is a function of both the size of the thermal and its distance. I can see how spatially separated signs (trees, streamers, etc) would help triangulate, but what if don't have those?
 May 05, 2012, 09:33 AM launch low, fly high New Zealand, Hawke's Bay, Havelock North Joined Dec 2004 2,132 Posts Rate of change of the wind provides a strong indication of size and distance.
 May 05, 2012, 03:01 PM Come out swinging San Diego Joined Mar 2005 2,739 Posts Joe, Can you explain why you want to fly along a straight path and how to interpret model response and what it means in terms of the thermal's position? Sean
 May 05, 2012, 04:32 PM Throw it like you hate it United States, CA, Castro Valley Joined Apr 2007 3,115 Posts weird double post
 May 05, 2012, 04:33 PM Throw it like you hate it United States, CA, Castro Valley Joined Apr 2007 3,115 Posts if i assume the thermal is tracking downwind with the prevailing wind, and the prevailing wind is constant in both velocity and direction, then can i tease apart both the size AND distance of the thermal? for instance, if the thermal is close to me the third vector will rotate quickly, while if the thermal is very far off, the third vector will rotate slowly. this is like looking at a commercial jet high in the sky, and it looks like its going very slowly, but in reality it is moving fast. only because we are far from it, does it look to move slowly. is this a correct way to determine distance? magnitude and direction of the third vector gives information on both size and distance, but from this alone i cannot determine both the size AND location independently. correct? we need look at how the third vector evolves? paul
 May 05, 2012, 06:08 PM up from the skies United States, CO, Fort Garland Joined Jul 2011 591 Posts What's a vector-sorry I don't know that stuff Tom
May 05, 2012, 06:42 PM
American Exile
Germany, BB, Nauen
Joined Jan 2009
344 Posts
Quote:
 Originally Posted by Tmfury What's a vector-sorry I don't know that stuff Tom
A vector is magnitude and direction.
May 05, 2012, 06:55 PM
Throw it like you hate it
United States, CA, Castro Valley
Joined Apr 2007
3,115 Posts
Quote:
 Originally Posted by Tmfury What's a vector-sorry I don't know that stuff Tom
this is the diagram to which Frank was referring. this should help relieve your confusion.
paul