This is a great subject but not often detailed in pictures. Cold and touch are the big stimulaters. I've not seen many before and after shots but there must be loads knocking about.
These examples were taken myself and will be part of my Holiday Videos set that I'm getting going in Sexy Videos.
Here are some screen shots of what I mean
The first two are before and after suncream application
The second two are from a sunny but windy beach. I'm going to add a speeded up video of the second pair which shows the whole breast changing in size as the nipples harden.
Here is the link
https://forum.oneclickchicks.com/show...15#post1307115