Mountain Meteorology in Action

I was lamenting on what a bad decision it was not to take my new watch (re Blog of 12th October 2008) on my recent trip to Peru and the chance I would have had to give it a good test out in the Andes and to take a meteorological observation in Machu Picchu (what a fantastic place to visit by the way – twice as good as any photos you might have seen).

Fortunately the plane I travelled in was an Airbus with one of those screens that gives you temperature at different altitudes, so on take-off and landing I had the chance to record some upper air observations, and here are a couple below relating to my landing and then take-off at Lima airport:



You can see that they certainly do not conform to the ‘standard atmosphere’ (as defined by the International Civil Aviation Authority) of temperature changing by around 6°C per kilometre. Coming into Lima (blue line) you can see a warm layer of air just below 2 km that extends right down to about 700 m.

The flight from Lima into Cusco was an example of some of the challenges that aircraft have at high altitude. The landing is very spectacular as the plane circles around the mountains and comes into land in a shallow valley at around 3,600 m. You can hear the engines at high revs in the closing turns to maintain the lift they need to turn in the much thinner air (lower air pressure).

I was hoping to see some of my favourite lenticular clouds in the mountains, but not this time. However I did see some amazing cloud formations. Here is one example below; along with a picture I took at sunrise coming through the clouds as I travelled out of Cusco on a train to Machu Picchu.