Contrail analysis - what do your observations show?

Dr Geoff Jenkins, from the Royal Meteorological Society, has analysed  some of your observations and compared them to what we might expect. Do your observations match these expectations?

8-9 May 2011 - no contrails to be seen

What were the conditions like?

Humidity at altitudes where aircraft cruise was extremely low - as low as 20% over most of England. This is so low that water vapour from jet engines would immediately evaporate, before it had a chance to form even short contrails.

What types of contrails would we expect to see?

No contrails across the country.

So what did your observations show?

Only one contrail was spotted - a short one over London.

 

9 April 2011 - an east-west divide

What were the conditions like?

Humidity at the heights aircraft cruise was high over the western parts of the country but lower over eastern parts.

What types of contrails would we expect to see?

Long, spreading contrails in the west (high humidity) and short or no contrails in the east (low humidity)

So what did your observations show?

A clear divide on the map can be seen, showing spreading contrails in the west and short contrails in the east. Only a few observations where made in eastern England but they were all of short or no contrails.

 

11 March 2011 - a day of long and spreading contrails

What were the conditions like?

The computer model shows that over England and Wales the humidity was high at altitudes where most aircraft cruise.

What types of contrails would we expect to see?

At high humidity we would expect contrails to be long or spreading.

So what did your observations show?

• 115 observations received on 11 March 2011
• Many observations of long and spreading contrails across most parts of England and Wales
• A few reports of no contrails - probably due to no aircraft flying at the time
• A few reports of short contrails - these could be from aircraft flying at a lower or higher altitude, where humidity is not so great

 
We expected to see long or spreading contrails and this is what your observations on 11 March 2011 show.

 

7 March 2011 - a day of short contrails

What were the conditions like?

The computer model shows that over England and Wales, the humidity was very low at the altitudes where most aircraft cruise.

What types of contrails would we expect to see?

At low humidity we would expect contrails to be short.

So what did your observations show?

• 128 observations received on 7 March 2011
• Many observations of short contrails across most parts of England and Wales
• Some reports of no contrails, probably due to no aircraft flying at the time
• Very few reports of long contrails
• No spreading contrails reported

We expected to see short contrails and this is what your observations on 7 March 2011 show.