Mid Layer Recommendations

[Ron]

well, to each their own! I dont use eVent and Neoshell just for those purposes (too much venting of heat) for inbound resort use but gore-tex Proshell (pick one, there's 3 now) IMHO is the absolute best for shell materials, it is nearly waterproof while still highly breathable and windproof while maintaining a high level of durability, even in the 40 denier weight.

Sorry, all hard-shells are not waterproof 10K is def not waterproof, it can wet through fairly easily in resort use. of course, the DWR is much more important than most understand. The line between fabrics is getting blurred, there are some pretty supple gore-tex fabrics (C-Knit) . https://www.gore-tex.com/blog/lab-7 for instance.

 

[Slim]

Yep, @Ron , we agree on the actual physics, this was just a matter of naming.

 

[Dr. Mark]

Patagonia R2. The regular version, not the techface. No matter how many newer mids I buy, I always come back to this one.Lightweight, fluffy, warm. Perfect.

I am the same way with my R1 hoodie.

 

[noobski]

Plenty of people do - whether for lower weight overall or a slight gap to their base layer or because of off-construed ideas about bulk=sweatiness.

This is partly why and...

As to the why, I don't know why @noobski does it.

I wear those types of garments in that layering style, to be able to add and subtract layers. Ski bumps in my Nano Air, throw a shell over it on the lift or if it gets cold in morning or late afternoon.
Skin up in my Airshed or similar, throw a shell or insulated jacket over the top for descending, that sort of thing.

With a less air permeable windshirt, people often wear it over their baselayer, under a shell to prevent flash off cooling. Purposely slowing moisture transport away from the skin.

* https://gearjunkie.com/patagonia-houdini-air-review
For more on the Airshed, see here: https://maxneale.blogspot.com/2018/11/ultimate-alaska-backpacking-gear-list-part-one-clothing.html

... This is also why

...AND the shirt goes over my Capilene Air Hoody so when combined: thin, but warm and quasi wind-proof.

However it's all anecdotal. I found it just to be a super thin layering with the same relative warmth ratio as if I was putting on a t-shirt + 200+base + wool sweater, while never sweating. But really the foundation of all of this is the Capilene Air Hoody. I love that piece plus the hoody can serve as a quasi face covering in lift lines.

 

[GSG43]

Look into the Arc'Teryx Delta LT Zip Neck. It is pretty thin but very warm. I wear a long sleeve Hot Chilly base layer, then the Delta LT and then my ski jacket and that works for me