Question | Answer |
Water cycles through the earth the atmospheres | evaporation, transpiration, interception, infiltration, and condensation |
Evaporation | occurs if energy is available to a water surface |
Saturation | = equilibrium between evaporation and condensation adding more water vapor or additional cooling will lead to condensation in the atmosphere i.e. cloud formation. |
Humidity | the amount of water vapor in the air. Expressed in many ways: vapor pressure, saturation vapor, absolute humidity, |
vapor pressure | pressure exerted on the atmosphere by water vapor. dependent on temperature and density. |
Saturation vapor pressure | maximum water vapor pressure possible solely temp. dependent exponentially increases with temp. |
Absolute Humidity | density of water vapor in g/M^3 changes as air volume changes. |
Specific Humidity | a mass of water vapor per mass of air in g/kg does not vary with volume fluxes and does not change what temp. |
Mixing Ratio | amount of water vapor relative to only a mass of dry air and it’s a ratio. |
Relative Humidity | given as a % of water vapor amount relative to the saturation point. Depends on air temp/total water vapor present. I.E very inaccurate R.h can be very misleading. highest occurs during coolest times and vis a vis .cannot not be used to compare 2 differen |
Dew Point | temp at which saturation occurs. |
Dew point temp saturation. | temp to which air must be cooled without changing the water vapor content or the pressure to reach |
Frost point | Saturation occurs below the freezing point. |
Methods of achieving saturation | addition of water vapor, mixing cold air with warm moist air, cooling air to the dew point. |
Measuring humidity | sling psychrometer- two thermometers to measure wet and dry bulb temps. Aspirated and hair hygrometers are alternatives. |
Heat index | combines heat and humidity factors. |
High humidity | reduces evaporation |
diabatic process | the direct addition addition or removal of heat energy. |
The second law of Thermodynamics | energy transfers from areas of high temp to areas of lower temp. |
Dry adiabatic lapse rate | -1C/100m(-5.5F/1000Ft), sinking parcels experience compression warming. |
The environmental lapse rate | Overall decrease in air temp with height, Changes diurnally from place to place, air aloft is located farther from surface heating. |
Convergence | air converging into low-pressure regions. |
Localized convection | Free, Forced (mechanical). |
Clouds | instrumental to the earth’s energy and moisture balances, form as parcels lift and cool. Mechanisms that lift air = Orthographic lift, Windward Vs. Leaward -Rianshadow. |
Frontal lifting | boundaries between unlike air masses, warm/moist air rises to form clouds, cold and warm fronts occur. |
Static Stability | Atmospheric conditions relative to vertical air motions, Related to temp-controlled buoyancy, - positive and negative buoyancy. |
Types of Static Stability | Statically unstable, Statically stable, Statically neutral. |
Absolutely unstable | positive buoyancy, parcel cooling rates are less than that of ambient air. |
Absolutely stable air | Negative buoyancy, parcel cooler than the ambient air. |
Conditionally unstable air | nvironmental Lapse Rate is between the dry and adiabatic lapse rate and the saturated adiabatic lapse rate, negative buoyancy initially, positive buoyancy after saturation. |
Cloud types | nlimited variety of size, shape, and composition, classes based on appearance and/or height. Not all clouds precipitate, precipitation requires rapid cloud drop growth. |
Factors influencing the ELR | heating/cooling the lower atmosphere. Surface-based observations: Ceilometers, laser used. |
Clouds observation by satellite | visible images, infrared images. |
Saturated adiabatic lapse rate | occurs in saturated air, -.5C/100m(-3.3F/1000Ft). |
Growth in warm clouds | Collision-Coalesence, -Larger collector drops begin process,- responsible for most latitude precipitation events. |
Growth in cool and cold clouds | |
Bergeron process | coexistence of ice and supercooled water is critical, rapid growth of ice crystals, riming and aggregation, responsible for most mid and high latitude precipitation events. |
Forms of precipitations | Snow- bergeron process, riming and aggretion |
North American distribution = Topographic influences: Lake effect snow: Large bodies of water, snow stimulated as cold air passes over warmer lake surface(evaporation), - Destabilizes overlying atmosphere,-provides uplift, snow occurs in narrow bands in l | |
Cumulonimbus clouds | ice(top, fuzzy cloudy margins), liquid(bottom, sharp margin), and mix of ice and liquid(middle). |
Hail | Concentric layers of ice around graupel-up- and downdraft interactions in thunderstorms,- Great plains/highest frequency, - may grow to large size and cause significant damage. |
Rain | drop size greater than .5mm. |
Measuring precipitation | Standard raingages,- Sparse network. |
Sleet | ice crystals melt in an inversion then refreeze near surface. |
Freezing rain | Similar to sleet, but freezes at surface. |
Rain gage measurement errors | Point estimates/ wide variations across small spaces,- measurement errors- wind, residual water, non-level surfaces. |
Precipitation measurement by weather Radar | precipitation estimates, real-time information. |
Snow measurement | Accumulated snow measured, water equivalent of snow/10 to 1. |
Automated snow pillows | convert weight to water equivalent. SWE important in water resources planning throughout western states. |
Absolutely Unstable | Parcel cools slower than environment, parcel is buoyant and rises. |
Absolutely Stable | Parcel cools faster than environment, parcel is not buoyant, does not rise. |
Conditionally Stable | Environmental lapse rate between dry and wet adiabatic lapse rates, air is initially not buoyant, but become buoyant after saturation. |