There are 3 known weather phenomena associated with winter sports like skiing that can affect the safety of any trip, and these relate to the ability of skiers to see their environment clearly and their ability to cope with challenges to their depth perception. Those 3 weather phenomena are:
- Flat Light;
- White Out;
- Self Induced White Out.
Flat LightFlat light is an optical illusion commonly known as sector or partial white out, a condition which can cause a skier to lose their depth of field and contrast vision capabilities. This danger is commonly accompanied by overcast sky conditions which inhibit good visual cues, and occur in fresh snow covered areas. Flat light can completely obscure terrain features which can make it impossible to judge distance and closure rates. This reflected light can give skiers a lot of difficulty in seeing dangers ahead like trees, ice patches, boulders or other dangers. No doubt you have seen video on the late night news showing multiple vehicle accidents during the winter, most caused by visibility problems.
White OutThis situation occurs when the skier becomes engulfed in a uniform white glow which can occur when sking through a snow shower or snow storm. Because there are no shadows in this situation skiers can not see the horizon and all depth of field cues are lost. Because there are no visual references a white out situation can be very dangerous for skiers, therefore sking in white out conditions should be avoided.
Self Induced White Out[caption id="attachment_12366" align="alignright" width="300"] A Helicopter Accident Resulting From Self Induced White Out[/caption] Self induced white out is commonly associated with helicopter operations when arriving or departing a snow covered area. Rotor down wash picks up snow particles and recirculates them through the rotor system and can happen even on very bright days with good contrast and still result in a complete loss of visual cues. If the helicopter pilot has not prepared himself for this immediate loss of visibility the results can be disastrous.
When All Visual References Are LostWhen all visual references are lost skiers should first and foremost trust their instincts and pull over to the side of the trail followed by finding a way to exit the white out area and find outside visual cues. Getting caught in a no visual reference situation can be fatal. Physical awareness may tell you that you are skiing straight; however, you may actually find yourself rapidly approaching other unseen hazards that may cause you serious injury.
How To Lower White Out Risks
- Always leave yourself an out;
- Do not continue skiing when you have no visual reference left;
- Make sure you don't lose sight of your visual references points at any time, and never turn away from your reference point;
- ski with your head straight looking forward and always be aware of your surroundings and what is in front of you.