Introduction to Contrails/Chemtrails and Cirrus Clouds
To understand how trails form, it’s important to first understand some key concepts in atmospheric science, particularly how we use percentage numbers to describe the amount of ice in the atmosphere.
In everyday life, we think of 100% as the total amount, the “whole thing.” But in the atmosphere, things work a little differently, especially when we discuss Relative Humidity with respect to Ice (RHice).
What is RHice?
- The “relative” part refers to pressure and temperature, which scientists have already factored into their calculations.
- The “humidity” part refers to the amount of water vapour in the air.
When we talk about RHice, we’re really talking about how much water vapor could turn into ice, given the specific conditions of the air at the time. These calculations are well understood by science.
Sub-saturation, Saturation, and Supersaturation
- Sub-saturation: This is when RHice is below 100%. Ice crystals will disappear back into water vapour.
- Saturation: When RHice is equal to 100%, the air is fully saturated. It’s the equilibrium point, where no more crystals will grow, but none will dissipate either.
- Supersaturation: When RHice is above 100%. This is when ice crystals can form and grow into clouds.
The 100% RHice point is a calculated reference for saturation, and understanding the significance of the saturation point is key to understanding how cirrus clouds and trails form, grow and dissapate.
Why Can RHice Be Over 100%?
Ice crystals don’t usually form in perfectly empty air; they need something to start on. We see ice growing on surfaces, like a cold window, but not in the air in the room or outside. It’s the interaction with the surface that encourages ice to grow.
Because ice crystals resist forming without a surface, water vapor can build up in the air, and RHice can exceed 100% without forming ice crystals. The air then becomes supersaturated, meaning it is holding more water vapor than it can comfortably handle, but no ice forms until the conditions are right with the surface.
The Role of Ice Crystals and Nuclei
This is where ice nuclei come in. These tiny particles, like dust or other microscopic matter in the atmosphere, act as the seeds around which ice crystals grow.
Without these ice nuclei, ice crystals would not readily form, even when the air is highly supersaturated.
Information from this website will prove that trails have very small sulfur-coated particles, which are extremely hygroscopic in nature. They attract moisture from the air and encourage ice growth when the air is still only subsaturated.