Pattipola Tunnel No. 18 climatic divide: cold wet montane cloud forest vs dry Uva basin?
Why does walking through the 300-meter railway summit Tunnel No. 18 at Pattipola mark an immediate shift from wet western mist to dry eastern sunlight?
More
4 Answers from travellers
Tunnel No. 18 burrows through the main Central Highland continental divide ridge at 1,897 meters elevation. The western portal opens toward Horton Plains and Ambewela, facing moisture-laden clouds brought by the Southwest monsoon that produce cold drizzle, wet patana grasslands, and dense montane cloud forests. The eastern portal opens toward Ohiya and the Uva mountain basin. As air masses crest the ridge, they lose moisture through adiabatic expansion and drop down the eastern slopes as a dry, warm, rain-shadow wind (Cachan). Passing through the short tunnel takes travelers from dripping mist into clear blue skies within two minutes.
Walking through active railway tunnels is strictly illegal under the Railway Ordinance; train headlights cannot illuminate pedestrians along narrow curved tunnel walls.
Tunnel construction through hard quartzite and charnockitic gneiss required manual rock drilling and black powder blasting under British surveyor supervision in the 1890s.
Temperature differentials between portals create a continuous natural air draft that blows moisture vapor through the rock bore toward the dry eastern valley.
You must be logged in to post an answer.
Log In to AnswerRelated questions
- Wildlife parks in Sri Lanka beyond Yala - Wilpattu, Minneriya, Udawalawe - which is worth visiting?2 answers
- Kandy Esala Perahera - when does it happen, where are the best viewing spots, and how do I get seats?2 answers
- Arugam Bay vs Weligama for intermediate surfing - which should I choose and why?2 answers
- Best local food to eat in Colombo - where do locals actually eat and what should I try?2 answers
- How cheap can you realistically travel Sri Lanka on a shoestring - $25-30 USD per day?2 answers
- Ayurveda retreat in Sri Lanka - what to expect and how to find genuine treatment vs tourist trap?2 answers
Join a Crew
Kandy Perahera Live Tonight
Perahera Seats, Hotels & Roads
Dalada & Perahera Culture