English: As temperature is constant, so like the in the definition of ϕ we know that: $\varphi = \frac{P_{wv}}{P_{sat}(T)}$ As temperature is constant the saturation pressure is also constant.
Telugu: ఉష్ణోగ్రత స్థిరంగా ఉంటే , కాబట్టి φ యొక్క నిర్వచనం మనకు తెలుసు: $\varphi = \frac{P_{wv}}{P_{sat}(T)}$ remains constant.