The day I left London was a bit damp which made for a bit of vapor on departure. I was sitting almost directly over the wing. I couldn’t see in to the inlet but I could see vapor puffs in front of the inlet at lower speeds anyway. As we rotated and climbed out, there was plenty of vapor puffing over the upper surface, aided by climbing through a few patches of cloud. I had the video running the get a view of the moisture and here is what I got.
Rain forest conditions do tend to mean lots of moisture in the air. That much moisture means perfect conditions for the growth of lichen. The lichen do a great job of collecting the moisture from the air to keep them well watered. The way the water drops form on the surface of the plant can be really interesting. Just a small vibration would send them dropping to the plant life below but, for now, they were safe.
Getting shots of vapor is a popular thing when shooting fast jets. An airliner on a damp day can also result in some clouds being formed. While shooting something special at Oakland, I was getting a few shots to make sure the light metering was working as planned. A Southwest 737 came in and, as it flared for landing, it had a nice cloud of moisture form over the wing. Normally these things pop up further out on the approach and don’t make for a good shot but this one was close at hand.
Moisture in the air is not always what you want when you are out shooting aircraft. However, it does have its benefits if there isn’t so much of it that everything is either obscured or gray. The weather conditions over San Francisco Bay can be very localized and, as the planes come down final approach, they can go through quite a variety. I was out hunting for Air Force One a while back and I got some good examples of this.
The weather at SFO was actually quite nice (although not when Air Force one departed as I have previously written about). The sun was out and the sky was pretty clear. In fact, there was quite a troubling amount of heat haze. However, once you got towards the south end of the bay, there was pretty solid cloud cover. The planes coming in were in full IMC for a good portion of their approach. Somewhere in the region between Coyote Point and the San Mateo Bridge they would break out of the cloud cover. Then, for the next mile or so, they were in the clear but still in very humid conditions.
The result of this humidity was a lot of vapor forming up over the wings. The low speed and high lift configuration made the wings a good place to get cloud formations as the moist air passed over them. Additionally, the trailing vortices were showing up well as a result of the condensing moisture in them too. For quite a while, each aircraft showed similar patterns as it descended. The widebodies seemed to be better for showing this but that might just be a function of them being easier to see further away when the effect was most pronounced. The closer they got to the field, the less the effect until it was pretty much gone when they were on final approach.
If you want to get some nice vapor from an aircraft, start with a good, humid day. The hours after a storm are perfect since there is plenty of moisture in the air and the ground is wet meaning it will keep feeding the moisture for a while. Now you just need a big jet to climb out at high power settings. Enter an ANA 777-300ER stage left.
The engines were filling with inlet vapor as the beast hauled itself into the sky and the tip vortices were also doing their bit to pull the water from the air. The fact is was late afternoon so the sun was in a good position too meant that the combination was pretty ideal. We got a few like this for a while but eventually the humidity levels dropped and things returned to normal. Still, it was good for a while and there were other benefits to come.
There are some aerodynamic effects that always catch my eye when I am going through images and one of these is vapor forming in engine inlets. The combination of lower airspeed with high thrust settings and moisture can result in puffs of vapor forming in the inlet, either continuously or, more often, as little flashes of cloud. The F-16 can often demonstrate this phenomenon when taking off although the formation is a little way back in the inlet.
On a recent Red Flag, the F-16s were out in force and, since it wasn’t the hottest and driest day that Nellis can provide, they were getting a bit of vapor to show up. Here are a few of the jets squeezing the moisture out of the air (even though it is the opposite of squeezing that makes it happen!).
