#### Ross Marsden

##### Senior Member.

Continuing...Suppose the trails are chemspray for what ever purpose...

How much material is there in a trail that is 10 miles long, for the sake of argument. How many pounds of whatever it is, lets say alumina, is required to do that?

As it stands the thread has 66 comments (but only 40 are visible for some reason).OK, if no one else is going to have a crack at this, I will.

There is a web page that answers "How much does a cloud weigh?"

http://mentalfloss.com/article/49786/how-much-does...

It goes with 0.5 gram per cubic metre for water content. These units are unfamilar to youse in America so I will convert to the Imperial measures of ounces and feet.

At 28.3 grams per ounce and 35.3 cubic feet in a cubic metre, that works out to 0.000499 ounces per cubic foot.

That seems small. How small? Apparently there are 22700 grains in a pound of rice.

That is 1419 grains of rice in an ounce. So 0.000499 ounces is 0.709 of a grain of rice; less than one grain of rice in a cubic foot of air! Very small amount! Crikey... let's press on.

Consider a trail.. let's say its a couple of wing spans wide and deep, and 10 miles long.

At an altitude of 7 miles (36000 feet), and at an elevation of 45 degrees, 10 miles fits between your hands held up with 54 degrees between them; way less than horizon to horizon.

At the cruising speed of 511 mph a A320 covers 8.52 miles per minute which means 1.17 minutes (70 seconds) to cover 10 miles.

So a 10 mile trail is pretty short in the general scheme of things.

Pressing on...

width 200 feet, depth 200 feet, length 10 miles which is 52800 feet.

So the volume of our bit of trail is 2,112,000,000 cubic feet.

The trail contains material at the concentration of 0.000499 ounces per cubic foot.

That is 1054782.8 ounces;

divide by 16 to get 65923.9pounds;

divide by 2240 to get 29.4 tons.

So, 10 miles of trail weighs 29.4 tons.

Many of the planes seen making trails are A320s. According to the Wikipedia on the A320 family ( http://en.wikipedia.org/wiki/Airbus_A320_family )

the operational empty weight is 87000 pounds which is 38.8 tons.

Also the maximum take off weight is 150000 pounds which is 67.0 tons.

So the maximum payload plus fuel of an A320 is 28.1 tons.

But wait! The 10 mile trail contains 29.4 tons of material. That is MORE than the maximum payload total. We have not loaded any fuel, crew, passengers or their luggage and freight!

So the material in the trail is NOT coming out of the plane, is it.

Unfortunately it reads a bit disjointed because some commenters deleted their comments.