Over the past few months, I’ve received quite a few photos from viewers and taken a few myself showing contrails in the sky. Contrails, short for condensation trails, are the thin white lines left behind by jet aircraft as they pass overhead. They’re most noticeable on days when the sky is clear or mostly clear. This is one I captured during a morning walk.
This morning, when I opened my emai,l I found this question:
At the end of this article, I’ll address chemtrails, but let’s first address how these lines in the sky form.
Contrails form when the hot, humid exhaust from a jet mixes with the very cold air high in the atmosphere. When there’s enough moisture in that air, condensation occurs. Water vapor changes from a gas into tiny liquid droplets or ice crystals, creating the thin white streaks we see behind aircraft. These typically form at high altitudes, where temperatures are extremely cold, often colder than −40°.
It’s a process that’s very similar to what happens when you breathe out on a cold winter day and can see your breath form a small “cloud.” You may have noticed that on some days the cloud lingers, while on others it disappears almost instantly. The same idea applies to contrails. How long a contrail lasts depends on how much moisture is already in the surrounding air. Drier air leads to contrails that fade quickly, while more humid air allows them to linger and spread.
In this photo sent to Click2Pins from Toby in Lake Livingston, you can see this difference clearly. The lower airplane isn’t producing a contrail because it’s flying through dry air. Higher up, there are more contrails visible where the atmosphere contains more moisture.
Occasionally, a jet, especially while climbing or descending, will pass through layers of the atmosphere with different moisture levels. When that happens, the contrail can appear broken or segmented, rather than as one continuous streak. These gaps are simply a sign that the plane is moving in and out of drier and more humid air.
The history of contrails
Contrails were first observed during the earliest high-altitude flights in the 1920s. At the time, they drew little attention. That changed during World War II, when long-lasting contrails behind military bombers made aircraft visible from miles away and became a serious operational concern.
In 1953, scientist H. Appleman published a chart that could accurately predict when atmospheric conditions would allow contrails to form. That research is still relevant today. Modern military aircraft, including stealth bombers, use similar atmospheric guidance when planning missions because an aircraft isn’t truly stealthy if it’s leaving a visible trail across the sky.
Three kinds of contrails:
Depending on the atmospheric conditions, contrails will look different. These lines fall into three main categories: short-lived contrails, persistent contrails, and spreading contrails.
Short-lived contrails disappear within seconds. When the surrounding air is relatively dry, the tiny ice particles that form behind the aircraft evaporate almost immediately.
Persistent contrails, on the other hand, remain visible long after the plane has passed. These form in very humid air, and when wind shear is low, they can linger in the sky for hours.
Spreading contrails develop when moisture levels are high and the atmosphere is unstable or turbulent. As the name suggests, these contrails spread out over time, eventually taking on the appearance of thin, wispy cirrus clouds.
The photos below were taken around Houston and show each type. The persistent contrail is from a photo I took myself. The short-lived contrail was captured by Hoora Zaid, and the spreading contrail was submitted by Phredip through Click2Pins.
Addressing the elephant in the sky:
I know many of you have heard claims that the government, or some other agency, is spraying chemicals from aircraft. These claims refer to so-called “chemtrails” or chemical trails.
When you hear an extraordinary claim like this, it requires extraordinary evidence. Despite the emails I occasionally receive suggesting I’m covering something up, I’ve never been shown credible, verifiable evidence that supports the idea of chemical spraying. What we do have is well-documented atmospheric science that clearly explains how contrails form and why they sometimes look unusual.
Questioning what we see is healthy. But the explanations should be grounded in evidence, physics, and decades of research, not speculation.
If you believe we’re being poisoned from the skies, it’s worth pausing to ask a few basic questions. Why would this happen in broad daylight, where everyone can see it? Why not at night, or on overcast days, when visibility is poor? Forecasting cloud cover is relatively straightforward, so hiding such activity would be easy if it were actually happening.
It also raises practical questions. Do you know a pilot? Would someone you know really agree to harm themselves, their families, and their fellow Americans? And since contrails are observed all over the world, this would require a coordinated global effort involving countless pilots, airlines, and governments without a single credible leak or piece of evidence.
There’s also the bigger picture. Does any government agency truly need help from aircraft to harm public health? Most of us could improve our health far more by making better everyday choices, starting with diet.
From a technical standpoint, jet fuel does not contain metal-based compounds. Introducing dissolved metals would interfere with engine performance and stability, creating serious safety risks.
You may also be thinking of what you’ve seen at air shows, where smaller planes release a white trail. That effect comes from a separate attachment added to the aircraft, not from the engine itself. Some specialized aircraft also leave trails during cloud-seeding operations. Cloud seeding is a separate topic and one I’ll dive into another day.