So, corona loss of a high voltage transmission line passing through a hilly area may be higher than that of similar transmission line in plains due to the lower value of delta at high altitudes, that because when you are you know at higher altitude, particularly hilly area, your what you call that your I mean dust or dirt whatever it is, it is hill area in altitude it will be less as compared to the plain areas.
तर डोंगराळ भागांमधून जाणाऱ्या हाय वोल्टेज ट्रान्समिशन लाईन मधून होणारा कोरणा लॉस हा सखल भागांमधून जाणाऱ्या ट्रान्समिशन लाईन पेक्षा जास्त असेल, कारण समुद्रसपाटीपासून जास्त उंचीवर असणाऱ्या भागात डेल्टा कमी असतो.