A balloon having an envelope, a gas contained within the envelope, a payload connected to the envelope, wherein the envelope has a first portion that has a first absorptive or reflective property with respect to allowing solar energy to be transferred to the gas within the envelope, and a second portion that has a second absorptive or reflective property with respect to allowing solar energy to be transferred to the gas within the envelope where the second absorptive or reflective property is different than the first absorptive or reflective property, wherein the second portion is provided with a darkly colored surface that allows more solar energy to be transferred through the envelope to the gas within the envelope than the first portion, and wherein the envelope is rotatable to allow a preferred ratio of the first and second portions of the envelope to be positioned facing the sun.