For any glaciated activity you need to have rated category four glasses to protect your eyes from the reflection of the glacier and to avoid snow blindness. Exposure to solar radiation increases on average by 10% with every 1,000 meters (3,280 feet) of altitude. Even on cloudy days sun exposure in the mountains is extremely dangerous as you often will be in the top layer of clouds where the light intensity is much higher than down lower due to diffraction. The snow also reflects up to 90% of solar radiation in stark contrast to the 20% that is reflected on non-snowy ground. For example, fog still lets through 50% of sunlight without even considering the diffraction. Thus, in the mountains category four sunglasses are essential as their extremely dark lenses let in less than 8% of light.
In addition to the category four rating, you want to make sure that your glacier glasses have side shields as shown below. Nose shields while not required on our Cascade climbs are a great option to bring as well to protect your nose from sunburn while traveling on snow. You can easily purchase glacier glasses at our guide hut for your convince!
For people who wear prescription glasses there are a few different avenues that you can take when it comes to glacier glasses:
Prescription Glacier Glasses: This is a great option because you don’t have to worry about doubling up on glasses. Companies such as Julbo and Opticus make prescription glacier glasses that can be preordered to your specific measurement. Everything can be done on their website however it is important to make sure to order the glasses well in advance to make sure that they arrive in time.
Goggles: Goggles are a good option to put over your glasses when on the glacier, they likewise must be rated to category four to sufficiently protect your eyes. Goggles when mountaineering may not be the comfiest option as they are bigger and bulkier than glacier glasses. Julbo does make one pair of category four goggles that can be used for snow and mountaineering.
Glacier glasses are an essential gear item for any glaciated or snowy peak. Not having proper eyewear can put your summit attempt at risk due to the detrimental impacts that not using proper sunglasses can have on your vision. Before your trip make sure that you have the right glacier glasses to stay safe on the mountain!