ENVS 101 1st Edition Lecture 14 Outline of Last Lecture I. Water Under the GroundII. Water and SocietyOutline of Current Lecture III. Earth’s cover of Snow and Ice/ The CryosphereIV. Overview of Glaciers (Formation and Types) Current LectureCryosphere: This is the Earth system consisting of the perennially frozen parts of the Earth, (which are the parts of Earth which are frozen year-round) Includes things like sea ice, as well as glaciers. • Glaciers within this system cover a total of 10% percent of Earth's land surface.• Also included in this system is Frozen ground: which covers 20% of the Earth's land.Snow and ice reflect sunlight, increasing Earth's albedo (the more reflectance there is, the more albedo there will be as well) and effectively decreasing its temperature.Approximately 25% of the Northern Hemisphere land area is covered by snow, or has frozen ground during the winter. Snow melt is a critical component as a water source for rivers, and provides moisture for soilsPolar deserts: in polar regions annual snowfall is very low because the air is too cold for moisture. A surprising aspect of Earth’s North and South poles is that they are actually considered deserts, because there is very little precipitation in the air overall. In addition, the cold air that surrounds these poles cannot hold very much moisture at all. In comparison, very humid environments, that have water in the air tend to have much warmer air.A practical way of understanding this effect of temperature on how much water there is in their,is thinking of the process of boiling water. When water is exposed to higher temperatures in the air surrounding it, it readily evaporates. Because of the lack of water in the air and the size of the lands covering the poles, they are considered to have the lowest amount of precipitation on the Earth.The lower limit of perennial snow is called the snow line.These notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute.A glacier is a mass of snow and ice that is thick enough that the pull of gravity causes the frozen mass to move.There are several types of glaciers, defined by both their appearance and also where they are located. They include the following:- Cirque Glacier: the smallest. Used to be much larger during the course of last ice age that the Earth went through, but melting overtime has caused them to look much smaller- Valley Glacier: extends down from a cirque.- Ice Cap: cover mountain highlands or low lying land that is at high altitudes. These will often form radially outwards. Oftentimes when glaciers encounter a steep slope in their environment, they will end up cracking and splitting, causing ice falls as a result.- Fjord Glacier: A glacier in a fjord (which is a valley that is filled with ocean water)- Piedmont Glacier: spreads out from a valley glacier.- Continental Glacier: Enormous in size. Greenland and Antartica include 95% of Earth's glaciers and reach 3000 meters thick (about double the elevation of the distance from Albuquerque up to the top of the Sandia Mountains - Ice shelves that are hundreds of meters thick occupy Antarctica's embayments. Glaciers form from compacted snow -> as snow becomes firm -> eventually yields -> ice- Ice is impenetrable to the air, and because of this characteristic, it traps bubbles of air. If a sample is carved out from different parts of the glacier, air bubbles that are tens of hundreds of years old can be released from the ice and captured.Glacier ice is considered a rock. Additionally, snow, as well as natural ice, are often considered tobe mineralsIce grains recrystallize at depth within the glacier, reaching one centimeter near the base, an effect that is also known as snow metamorphosis.Glaciers from whenever snow and ice accumulate, in high latitudes, and high mountainsIce temperatures will also vary among glaciersWarm (temperate) glaciers at pressure melting point, can coexist with waterCold (polar) glaciers below pressure melting point (frozen to bed) A glacier's advance or retreat is the balance of the amount of snow and ice that is added (accumulation) and lost (ablation)• The upper zone is the accumulation area• Below this is the ablation area• Between these areas, there is the equilibrium line• The front of the glacier is called the