In the troposphere the atmospheric pressure decreases about 10 kPa and the temperature decreases about 279 K for every kilometer above the earth's surface you go. As a weather balloon released from the ground rises up will its volume increase, decrease or stay the same? Offer proof.

Answer 1

According to the web the temperature decreases about 10 C (10K) for every km. What I would do is assume a 1 km height increase.
P at surface is about 101 kPa.
T is about 298.
So P at 1 km is about 101-10 = ?
and T at 1 km is 298-delta T whatever that is. I think it's about 298-10 = 288

Then substitute into (P1V1/T1) = (P2V2/T2)
You can assume some volume for V1 and see if V2 is larger or smaller.