Good ol' Snow

Snow is white and reflective.  Meters are easily fooled as was yours in the first shot where the snow appears mostly grey.  When shooting snow generally adding +2/3 - 1.3 stops exposure compensation helps.  Your snow should almost match the white site background.

There are a ton of online photo sites that are helpful.

Have fun

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RonFrank
http://ronfrankweb.weebly.com/index.htmlw