Cold air drainage in SoCal

[elHoagie]

After the January cold, someone asked me about cold air drainage in SoCal (I think Matt in SD).  He wanted to know why higher elevations in SoCal were warmer during the freeze, but in places like Oregon and Hawaii higher elevations are colder.  To make a long story short, when there's a lot of clouds/moisture/wind in the atmosphere, then the temperature drops as elevation increases.  But, on clear/dry/windless nights cold air drainage becomes important, and it can be warmer at higher elevations on hillsides.

Anyway, it's been fun to track this at my new place in Los Angeles.  I'm near the official recording station in downtown LA, but my elevation is 200m compared to 50m for downtown.  We've had quite a few mornings with clouds or fog lately, and downtown is always 1-2C warmer than me on those mornings.  This is expected because the adiabatic lapse rate is about 1C/100m.  But, on dry, clear nights I'm about 1-2C warmer than downtown due to the better cold air drainage at my place.  On humid, clear nights I seem to record similar temperatures to downtown, indicating that my cold air drainage "cancels out" the adiabatic lapse on those nights.

[happ]

Appreciate your observations, Jack  

Mirrors my own data.  The transition is quite evident as I drive down into the city.  "Heat Island effect has to be factored in and how open wood/grasslands [native walnut] exhausts heat much faster.

What's interesting at my location is an overall similarity to USC minimums but not on the same date.  Example : the morning readings:  

Downtown : 54F/12.2c [normal 55F

Getty Museum : 58F/14.4c [also my value - norm: 56F/13.3c

Inversion is now below the foothills, allowing warmer days & nights.  Periodic night time warmth balances out monthly norms that equal downtown.

[Bilbo]

"Adiabatic Lapse" indeed.

Stop that now Jack - you maybe something big in Calltech - but what you meant was (in my own simple uneducated words) is that cold air flows downhill!

Yeah, I figured that out some time ago!

On a personal note which everyone will not read : isnt it about time we heard the pitter patter of little feet?

Love to Lauren - and remember I saved you for her from a den of iniquity.

Juan or Juanita would be a good name.

Regardez

Juan

[elHoagie]

Happ,

I had the same reading yesterday when it was clear and dry.  My low was 14C, downtown was 12C.  This morning, there is thick fog, and my low temperature was 13C, downtown was 14C.  Like you said, I think it evens out in the long run, but it's interesting that the readings are usually different each day.

Jack

[elHoagie]

(Bilbo @ Apr. 26 2007,03:57)

QUOTE

"Adiabatic Lapse" indeed.

Stop that now Jack - you maybe something big in Calltech - but what you meant was (in my own simple uneducated words) is that cold air flows downhill!

Yeah, I figured that out some time ago!

On a personal note which everyone will not read : isnt it about time we heard the pitter patter of little feet?

Love to Lauren - and remember I saved you for her from a den of iniquity.

Juan or Juanita would be a good name.

Regardez

Juan

Jon,

If I use big words it makes me feel smarter

Also, if you keep saying Lauren, then my wife Lindsey might think something is up!  And we already here the patter of little feet, we adopted our dog Moab from the humane society last month...

Jack

[happ]

Today is a yin/yan of onshore marine air:

Getty Center : 51F/10.5c

Downtown : 56F/12.7c

Cool at the beach/60's - warmer inland 70's-85F. Typical spring pattern.  Palm aficionados in Texas/Florida [lo : 60's/70's] can't relate to the long cool of California  :laugh:

Hotter this weekend  

[ruskinPalms]

Yeh, explain that a little more - Adiabatic Lapse. Does that have something to do with pressure?

[Bilbo]

Muchos apologias Jack; Lindsey it is.

Goodness knows who Lauren is?

Wow- thats got me thinking!

What have I been up to?

sorry for that boo boo BUT I did save you - and there are witness galore out there . . .

see you in CR I hope and in Teneriffe a couple of years later.

I shall be doing a "Pre-Tour"of Tener. in early July and will be based at the Sheraton - but then I dont mind sleeping rough.

Carlo is the best palm speaker I have ever met, indeed fluent in several languages, and Im not saying that just cos we have shared a beer or three.

Carlo has spent the EU cash wisely and concentrated on palms and not the hardscaping some guys might have done.

My thoughts exactly - but I just aint got the cash!

Regardez

Juan

[alex_7b]

How come those "Santa Ana's" don't blow in the dead of winter?

[happ]

(alex_7b @ Apr. 27 2007,12:05)

QUOTE

How come those "Santa Ana's" don't blow in the dead of winter?

Alex

Winter is when they do blow.  From late fall into early spring, the off-shore winds called "santa ana" are most active due to a variety of atmospheric conditions & can be very violent.

Normally from May thru September the westerlies [on shore] winds predominate though they are very light.  On the rare occasion of easterly winds during summer the weather conditions can be unbearably hot  

Today there is essentially neutral winds or diurnal [weak off shore in the morning and mild onshore breeze in the afternoon].  The beach cities are around 70F but much warmer just a few miles inland [near 90F].  This is a typical summer time pattern for California.

[STEVE IN SO CAL]

Jack...you hurt my feel bad.  You know I can't read c's and m's. Now I think you're doing it on purpose.  

Maybe it's all those c's that are causing global warming. We never had a problem til you guys started in with the c's.... ???

[happ]

:laugh:  Wish it were true  

Actually April has been mostly cool & probably below March readings [76/54F - 24.4/12.2c].

In fact, today was the first 90+ this month.  Heat in March occurred early.

Ocean temps Santa Monica bay barely 60F/15.5c - San Diego bay 63F/17.2c induce deep marine layer tendency.