Thermal Stress Crack In Window Fixed -

It may travel straight for a bit before branching or curving.

Tinted or heat-absorbing glass is much more prone to this. 💡 Pro Tip thermal stress crack in window

Thermal stress occurs when a "thermal gradient" develops. In a typical window, the center of the pane might heat up from direct sunlight while the edges remain cool because they are shaded by the window frame. Hot glass expands; cold glass does not. It may travel straight for a bit before branching or curving