Geology Chapters 4 5 Vocabulary Chapter 4 Evaporation suns energy transforms enormous quantities of liquid water into water vapor Condensation winds then transport the moist air to other regions where the water vapor changes back into liquid forming clouds Precipitation under certain conditions liquid or solid cloud particles may grow in size and fall to the surface rain snow hail Hydrologic water cycle cycle of moving and transforming water molecules from liquid to vapor and back to liquid again Sublimation ice to vapor change Deposition if a water vapor molecule should attach itself to the ice crystal the vapor to ice phase changes Saturated vapor pressure the maximum amount of water vapor necessary to keep moist air in equilibrium with a surface of pure water or ice represents the maximum amount of water vapor that the air can hold at any given temperature and pressure Absolute humidity Mass of water vapor Volume of air When comparing the vapor s mass with the volume of air in the parcel Specific humidity Mass of water vapor Total mass of air When the mass of the water vapor in the air parcel is compared with the mass of all the air in the parcel Mixing ratio Mass of water vapor Mass of dry air When the mass of the water vapor in the parcel is compared to the mass of the remaining dry air Actual Vapor Pressure the partial pressure of water vapor Saturation Vapor Pressure describes how much water vapor is necessary to make the air saturated at any given temperature saturation vapor pressure is the pressure that the water vapor molecules would exert if the air were saturated with vapor at a given temperature Relative Humidity RH Water Vapor Content Water Vapor Capacity or RH Actual Vapor Pressure Saturation Vapor Pressure The amount of water vapor actually in the air to the maximum amount of water vapor required for saturation at that particular temperature and pressure It is the ration of the air s water vapor content to it s capacity Supersaturated air with a relative humidity greater than 100 percent Dew point temperature Dew point 10 degrees Celsius Frost point when the dew point is determined with respect to a flat surface of ice Wet bulb temperature the lowest temperature that can be reached by evaporating water into the air Heatstroke complete failure of the circulatory functions body temperature must be above 41 degrees Celsius Heat Index used by National Weather Service to determine apparent temperature Apparent Temperature what the air temperature feels like to the average person for various combinations of air temperature and relative humidity Hygrometers instruments that measure humidity Hair Hygrometer constructed on the principle that the length of human hair increases by 2 5 percent as the relative humidity increases from 0 to 100 percent Vocabulary Chapter 5 Dew water that has condensed onto objects near the ground when their temperatures have fallen below the dew point of the surface air Frozen Dew the transformation of liquid dew into tiny beads of ice when the air temperature drops below freezing Condensation Nuclei tiny particles upon whose surfaces condensation of water vapor begins in the atmosphere Hygroscopic the ability to accelerate the condensation of water vapor Usually used to describe condensation nuclei that have an affinity for water vapor Hydrophobic the ability the resist the condensation of water vapor Usually used to describe water repelling condensation nuclei Haze fine dry or wet dust or salt particles dispersed through a portion of the atmosphere Individually these are not visible but cumulatively they will diminish visibly Fog a cloud with it s base at Earth s surface Acid Fog acid rain combined with fog droplets Radiation Fog fog produced over land when radiational cooling reduces the air temperature to or below its dew point also known as ground or valley fog Advection Fog occurs when warm moist air moves over a cold surface and the air cools to below its dew point Advection Radiation Fog fog that forms as relatively warm moist air moves over a colder surface that cooled mainly by radiational cooling Upslope Fog fog formed as moist stable air flows upward over a topographic barrier Steam Fog forms when cool air moves over warm water Winter Chilling the amount of time the air temperature during the winter must remain below a certain value so that fruit and nut trees will grow properly during the spring and summer Cirrocumulus a high cloud that appears as a white patch of clouds without shadows consists of very small elements in the form of grains or ripples Cirrostratus high thin sheetlike clouds composed of ice crystals frequently cover the entire sky and often produce a halo Altocumulus a middle cloud usually white or grey often occurs in layers or patches with wavy rounded masses or rolls Altostratus a middle cloud composed of gray or bluish sheets or layers of uniform appearance in the thinner regions the sun or moon usually appears dimly visible Nimbostratus a dark gray cloud characterized by more or less continuously falling precipitation it is rarely accompanied by lightning thunder or hail Stratocumulus a low cloud predominantly stratiform with low lumpy rounded masses often with blue sky between them Stratus a low gray cloud layer with a rather uniform base whose precipitation is most commonly drizzle Cumulus a cloud in the form of individual detached domes or towers that are usually dense and well defined has a flat base with a bulging upper part that often resembles cauliflower Cumulonimbus an exceptionally dense and vertically developed cloud often with a top in the shape of an anvil Often accompanied by heavy showers lightning thunder and sometimes hail thunderstorm cloud Lenticular Clouds a cloud in the shape of a lens Banner Cloud a cloud extending downwind from an isolated mountain peak often on an otherwise cloud free day Pileus a smooth cloud in the form of a cap occurs above or is attached to the top of a cumuliform cloud Mammatus Clouds clouds that look like pouches hanging from the underside of a cloud Contrail a cloudlike streamer frequently seen forming behind aircraft flying in clear cold humid air Nacreous Clouds clouds of unknown composition that have a soft pearly luster and that form at altitudes about 25 to 30 km above earth s surface Noctilucent Clouds wavy thin bluish white clouds that are best seen at twilight in polar latitudes form at altitudes about 80 to 90 km above the surface Geostationary