Yes, and if you are moving backwards within that mass of air ie with a 5 kt tail wind, and you want to move forwards in that mass of air ie to achieve a 30 kt headwind, then it will take longer to achieve than if you were already moving forwards in that mass of air ie a 5 kt headwind. It doesn't matter what the earth beneath you is doing, it's all about TAS and going from a negative to a positive rather than from a positive to a larger positive.