Slippery conditions can arise in as many as 15 different ways or different weather conditions. Knowing the mechanisms behind slipperiness helps prepare for slippery conditions. Unlike rain, which is visible and should cause a driver to sharpen their senses, slipperiness cannot always be perceived by the naked eye.

Ice can form on the road surface in the following ways:

• black ice: the road surface freezes rapidly and sucks moisture from the air to its surface
• ground frost: after sub-zero temperatures, the weather becomes milder, causing the cold road surface to suck in moisture, which freezes the surface
• sub-zero slipperiness: in extremely cold weather, the temperature fluctuates constantly (between -10...-20, for example), causing the moisture in the air to condense into ice on the road surface
• rime: fog or otherwise moist air condenses on the cold road surface
• freezing rain: freezing rain turns into ice when it touches the road surface
• rainfall on cold road surface: the road remains cold after a period of sub-zero weather, and the weather turning milder can easily result in rain
• wet road surface freezes: the road surface is wet after a moist day or due to meltwater

Slipperiness related to snow:

• wet snow: snow condenses on the road surface and becomes polished as a result of traffic
• the surface of a hard condensed snow layer freezes: the surface is moist or moisture condenses on it from the air
• the surface of a hard condensed snow layer melts and becomes wet: during a long period of warmer weather
• snow does not condense: under specific moisture conditions, snow turns into mush
• loose snow: a high amount of loose snow can lift a car’s tyre off of the road surface
• slush: slush can easily lift a car’s tyre off of the road surface