Where are some examples of nature's sympathetic response to mankind in The Scarlet Letter?
The first example where we witness nature being sympathetic toward mankind is in chapter 1, "The Prison Door". Here is where Hawthorne dedicates an entire mention of praise toward the rosebush that is growing by the prison. Right from the start, Hawthorne describes, from the inside and outside, the environment where Hester has been imprisoned. His description talks of a place where Puritanism is so intense that everything is seen under a negative, dark, and sad light.
...sad-colored garments, and grey, steeple-crowned hats, intermixed with women, some wearing hoods and others bareheaded, was assembled in front of a wooden edifice, the door of which was heavily timbered with oak, and studded with iron spikes...
This suggests that the place is meant to be colorless, dark, and somber. However, despite the sadness of the place, and despite the location where it has decided to grow, the rosebush is there at the prison door symbolizing that the nature of the earth supersedes human nature, and can be forgiving and embellishing even when our souls are rotten with sin.
It is colorful, strong, and has been there despite being darkened by the oak trees that grow tall around it. It is resilient, and it is fearless. Most of all, it is sympathetic to our humanity regardless whether we have a lot or very little of it.
Another example of nature being sympathetic is the forest. Notice how the forest serves as a point of contact between Hester and Dimmesdale, where they can feel safe to speak and share their secrets. Ironically, the forest is also hostess to Mistress Hibbins, the town's witch, who enters and exits it to do her biddings as she wishes. The forest is as sympathetic to Hester as it is to Hibbins. It protects them both, hides them both, and seems to understand the motives of both women, regardless of what those motives are.
Keep in mind that in Romantic literature nature is exalted and used to the fullest. This is why, in this novel, you will see that some characters, such as Pearl for example, are entirely interconnected with nature, responding to its whims and caprices, and vice versa. The weeds growing in the cemetery, the herbs Chillingworth uses to soothe both Pearl and Hester in prison,and the meteor that shines in a red letter "A" in the sky in chapter 12 are also other examples of nature being always willing to show its best face to humanity despite the latter's flaws.