what causes silver thaw

Silver thaw is caused by liquid rain falling into a shallow layer of subfreezing air near the ground, so the drops are still liquid when they reach the surface but freeze instantly on contact, coating everything in clear ice.
What is âsilver thawâ?
- Itâs another name for freezing rain or glaze ice in many places (especially parts of Canada and the Pacific Northwest).
- It leaves a glassy, transparent coating of ice on trees, roads, power lines, and other exposed surfaces, giving a shiny âsilverâ look.
The stepâbyâstep cause (weather setup)
- Cold ground and nearâsurface air
- There is a recent or ongoing freeze, so the ground and objects like trees, cars, and wires are below 0 °C.
- Warmer air above (a temperature inversion)
- A layer of air a bit higher up is above 0 °C, warm enough to melt snow into raindrops as it falls.
- Shallow subfreezing layer near the ground
- Just before reaching the surface, raindrops pass through a thin layer of air that is below 0 °C, but the layer is too shallow for the drops to refreeze into ice pellets; they stay as supercooled liquid.
- Instant freezing on contact
- When those supercooled drops hit anything colder than 0 °Câroads, branches, power lines, sidewalksâthey freeze on impact and build up a smooth, clear glaze called silver thaw or glaze ice.
In plain language: snow melts into rain in a warm layer aloft, then that rain becomes supercooled just above the ground and âflashâfreezesâ onto anything it touches.
Why it looks âsilverâ
- The ice layer is usually clear and uniform, so it reflects and refracts light, making trees, fences, and wires sparkle like glass or metal.
- After a severe frost followed by this kind of freezing rain, landscapes can look as if theyâve been dipped in glassâthis striking appearance is what the term silver thaw refers to.
Related terms you might see
Hereâs a quick reference in HTML table form, as you requested:
| Term | What it means | How it relates to silver thaw |
|---|---|---|
| Freezing rain | Rain that freezes on contact with surfaces at or below 0 °C. | [3][1]Physical process that causes silver thaw. |
| Glaze | Smooth, glassy ice coating formed by freezing rain. | [5][9]The ice layer produced during a silver thaw event. |
| Silver thaw | Glassy ice on surfaces from freezing rain or refreezing meltwater, often after a hard frost. | [7][9][5]Descriptive/local term for the whole phenomenon. |
Mini âstoryâ example
Imagine a cold winter night after a deep freeze. The air a few hundred meters up warms just enough that falling snow turns into regular raindrops, but the streets, trees, and power lines are still well below freezing. The rain feels like normal rain on your jacket, yet every drop that lands on a branch or the road instantly turns to ice, layering up millimeter by millimeter. By morning, every twig is encased in crystalâclear ice, cars are locked in place, and roads are slick glassâthat shimmering, dangerous scene is a classic silver thaw event.
Information gathered from public forums or data available on the internet and portrayed here.