3 Questions

[Bodhi]

Dear All,

I just spent half an hour writing this post and when I sent it the forum had logged me out and the post was lost. I'll rewrite it but much more succintly as I'm low on time now. Thanks for any replies.

1) Local lower wind clouds colliding - one set from NW, the other from S. Neither a sea breeze. How is this possible and can I predict it via obs or charts?

2) Ac layer moving at approx 30 degrees to a lower Ac layer, that in turn was moving at almost ninety degrees to the low cloud. Is there any information oout there on the basic physics of this and an explanation?

3) Highest insolation, bith incident on atmosphere and at ground (Ahren's) at 30N in the n hemisphere. If the Hadlley cell is driven by thermal winds created near the equator and sending upper level wind polewards due to the gradients established, then why isnt 30N the uplift region for the hadley cell in summer when it has a higher insolation than the Equator. Why is it still the rough area for sinking air?

I appreciate any help. Thanks.

Rich

[Jo Farrow]

1 you can get local convergence of winds, often most influenced by topography. Local knowledge is often the best way to forecast these lines which can result in showers on otherise fine day

2. different levels of the atmosphere have different winds WV CB, warm advection veering, cold advection Backing with height

 

What is driving your questions Bodhi, quite a mixture ?

[Nick F]

With regards to question (1), current wind obs can be useful in showing wind convergence, as Jo suggests the reason for the clouds 'colliding', xcweather I sometimes use to pick out winds converging (i.e. opposing wind directions meeting):

http://www.xcweather.co.uk/

Netweather extra (and maybe free?) has GFS wind streamline charts that can pick out lines of covergence too, bearing in mind wind conv. can form from synoptic flow as well as sea breezes which aren't modelled so well:

 

[Jo Farrow]

1. so you could see the likelihood of convergence lines from surface wind charts, or as Nick says use the streamline charts. The peninsula of Cornwall and Devon often see showers lining up in this setup

[Bodhi]

Hi folks,

Thank you for your replies.

Firstly to Jo: Thanks. I'll look up the warm /cold advection.

In answer to your question. I am eternally curious and a single question often leads me down a complex rabbit hole of further questions. I taught myself a lot of meteorology a few years back when learning bushcraft and survival skills. I thought it'd be great to be able to predict the weather in order to know when to build shelter early and organise different outdoor tasks. Recently I was out explaining bits and pieces to an interested party on things like natural navigation and weather front clouds, and this reinspired me to start regular sky watching again. Then I noticed these phenomena . I also saw, from the same position at a different time,low  clouds following a curved path.

Secondly to Nick: Thanks - I am about to check out those links after replying to you.

OK its good to know that synoptic flow can also do this.

I have a little more info on the situation after someone showed me the Kinloss METARs for the time period. Kinloss picked up the two winds at slightly different times. I'm guessing that a siungle station has no way of differentiating between one wind veering and two winds colliding necessarily. Ayway the METAR shows winds 200 veering to 280 and then 060. The 060 would make a shallow angle wind to the coast, coming in from the right- I am informed that this is indeed likely to be a sea breeze.

Just as an aside my father was born and raised in South Norwood.

Best wishes,

Rich

[Bodhi]

I have just seen the wind obs map on xcweather and notice that there are a number of places where winds are moving differently to synoptic patterns. Middle England shows divergence just in from the Weslh border and then reconvergence at the top of East Anglia. My location shows Westerlies, bending from a general SW flow- although slightly lower down the flow has turned Northward along the Aberdeenshire coast.

Does anyone know if there is a book that gives all the different surface wind modifiers and how they interact, please?

Cheers,

Rich