Snow that does not melt or sublimate (turn into water vapor) can build up to form glaciers and ice sheets1. More snow accumulates each winter than melts each summer: snow depth gradually increases2. Melting and refreezing changes shape of crystals then pressure recrystallizes deep snow into denser ice with less air pressureIn Glacial IceAir bubbles -> atmospheric compositionIce isotopes -> atmospheric temperatureIncreased pressure over time causes ice crystals to grow large and larger1. More snow accumulates each winter than melts each summer: snow depth gradually increases2. Pressure recrystallizes deep snow into denser ice with less air space3. Eventually ice and snow become so thick that the pull of gravity causes the frozen mass to move4. A glacier is formed-Be able to classify a glacier (based on temperature or shape) from a photo/image Glacier – a permanent body of ice, consisting largely of recrystallized snow, that shows evidence of slow downslope or outward movement due to its own weightClassified based on shape and base temperatureTypes based on shapeCirque glacier – occupies a bowl-shaped depressionValley glacier – when as cirque expands out and flow downward into a valleyTidewater glaciers – when a valley glacier reaches the seaIce caps – miniature ice sheets covering < 50000 km^2, form in relatively flat but high elevation areas. Ice flows away from the highest point towards the edge, often via glaciersIce sheets – only found in Antarctica and Greenland toady, continental sized masses of ice covering > 50,000 km, also extremely thick covering almost all land featuresIce shelves – only found around Greenland and Antarctica today,occur where ice sheets extend over the sea and float on water, between 250, to 2.5km thickTypes based on base temperatureTemperate glaciers – where atmospheric temperatures high enough for the glacial ice to be at or near its melting temperaturePolar glaciers – where atmospheric temperatures are so low all year thatthe glacial ice stays well below its melting temperature-Be able to describe/explain/predict where the different glacier types will be found (altitude/latitude) and what factors will affect them e.g. air temperature, ocean temperature, precipitation amount etc.