Water changes & Cycle Page 17 of INB

Temperature is a measure of kinetic energy - Every atom or molecule has a certain amount of kinetic energy Formula is kinetic energy = ½ mass x velocity2 Temperature is a measure of the average kinetic energy of all the atoms and molecules within a substance. Temperature is measured in degrees using either Fahrenheit, Celsius, or Kelvin. In this class, we will use Celsius.

States of matter Water exists in three physical states: solid, liquid, and gas. - Solid water is called ice. All water molecules in ice are packed closely together and vibrate in place. - Liquid water is more dense than solid water. Water molecules in liquid water run past one another smoothly, forming the shape of their container. - Water in gas form is called water vapor. Water vapor molecules have the highest kinetic energy and fill the shape and volume of their container.

Oceanic solid water: Sea Ice Sea ice forms as seawater begins to freeze forming “frazzle.” Sheets of new sea ice are broken into “pancakes.” Pancakes then move, unite, and form “ice floes.” Oce floes move with the currents and wind. Stationary floes that attach to land are called fast ice. Sea ice does not contain any of the dissolved salt of seawater. The left behind extremely salty, extremely cold water sinks, pushing up fresher water for the continued formation of additional sea ice.

Oceanic solid water: Icebergs Freshwater glacial ice covers much of Greenland and the Antarctica continent. When a piece of land ice breaks off and falls into the sea (called calving), these pieces are called “icebergs.” Icebergs are massive, irregular floating shapes, with only 12% of the mass seen on average above water. Icebergs drift with currents and often do not escape into the ocean, but hug the coastline of the nearest land mass.

Changing State Pure water ice melts at 0 degrees Celsius Pure water boils at 100 degrees Celsius Because of the hydrogen bonds, it takes a lot of energy or heat to separate them from each other. Heat is the total kinetic energy of all the atoms and molecules in a substance. The larger the body of water, the greater heat it has because the more atoms it has.

Which has more heat? Compare a pot of boiling water on your stove with a swimming pool on a warm day. Which one has more heat? Why?

Key terms: Changing state Dew Point – the temperature when water vapor (gas) condense to liquid Latent Heat of Vaporization – the heat needed for a change between liquid and vapor (gas) Latent Heat of Fusion – the heat needed for a change between solid and liquid

Specific heat One gram of liquid water requires 1 calorie of heat to raise its temperature one degree Celsius. Water changes its temperature the least for the addition or removal of a given amount of heat. This is because water has a very high specific heat compared to soil, rocks, or air. Specific heat of a material is the quantity of heat required to produce a unit change of temperature in a unit mass of that material.

Hydrologic (Water) Cycle Water cycles through the oceans, rivers, lakes, below the ground, glaciers, snow packs, sea ice, and the atmosphere. Each of these places – or any place that water resides - is called a reservoir. The movement of water through the reservoirs is called they hydrologic cycle.

Hydrologic Cycle: Key Terms - Water is taken out of the ocean and moved into the atmosphere by evaporation. Precipitation is when water returns from the atmosphere in the form of rain, snow, sleet, or hail. Transpiration is the release of water by plants. Sublimation is the conversion of ice directly to water vapor (skipping the liquid stage); generally happens within clouds

Residence Time - Because the total amount of water on Earth is essentially constant, the hydrologic cycle must maintain a balance between the addition and removal from Earth’s reservoirs. - The rate of removal from a reservoir must equal the rate of addition - If it does not, one reservoir will gain at the expense of another (think about melting of the ice caps currently – it is adding to the ocean reservoir and taking away from the ice caps) - The average length of time that a water molecule spends in any one reservoir is called the residence time.

Residence Time Large reservoirs, like the ocean, generally have a longer residence time, while small reservoirs like rivers generally have a short residence time. The size also determines how a reservoir reacts to changes in the rate at which water is gained or loss. Larger reservoirs will react less to changed but small reservoirs will change substantially.

Earth’s Water supply Oceans and sea ice - 97.26% Ice caps and glaciers - 2.11% Ground water - 0.60% Freshwater lakes - 0.009% Saline lakes and inland sea - 0.008% Soil moisture - 0.005% Atmosphere - 0.001% Rivers - 0.0001% Total cubic miles of water worldwide: 332,940,400 Total cubic kilometers of water worldwide: 1,387,897,750

Key Points Temperature is a measurement of kinetic energy. Solids have the least kinetic energy, gasses have the most kinetic energy. Water is unique in that its solid (ice) is less dense than its liquid. Sea ice and icebergs float on top of ocean water. Heat is the total kinetic energy of all the molecules in a substance. The larger the substance, the more heat is contains. Water has a high specific heat, meaning that it takes a lot of energy to make water undergo a phase change (from solid to liquid or liquid to gas). Water molecules travel through different reservoirs as part of the hydrologic cycle. Some of the largest reservoirs are ocean water, ice, and the atmosphere. 97% of Earth’s water is in the ocean. The other 3% is freshwater.

Water Cycle Game You are all now magically transformed into water molecules. You are going to begin at the station closest to you and travel to different reservoirs by rolling a dice and following the directions. At the end, you will answer the questions on the Water Worksheet (whatever is not finished becomes homework).