I am eight letters long - "12345678"
My 1234 is an atmospheric condition.
My 34567 supports a plant. (the same word, spelled differently is a favorite meal).
My 4567 is to appropriate.
My 45 is a friendly thank-you.
My 678 is a name.
Q: What word am I?
This a good puzzle except I don't understand the friendly thank you part. Have fun.