GHY 104 1st EditionExam # 3 Study Guide Clouds and Fog- Collison-Coalescence process- Beregeron process- Occurs in the higher parts of the troposphere.- Decreased pressure means both liquid water and solid water (ice) can co-exist.- Liquid water can be super-cooled below freezing- Liquid water sheds water molecules which are absorbed by growing ice crystals- Eventually snow falls, or melts during descent into rain. - Cloud types and Identification- Altitude and shape – key to cloud classification - 3 basic forms of clouds:  Flat Puffy  Wispy- 4 Altitude classes: Low  Middle High Vertically developed- 10 basic cloud types: Cirrus Cirrostratus Cirrocumulus Altocumulus AltostratusThese 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. Stratus Nimbostratus Stratocumulus Cumulus Cumulonimbus- Stratiform – horizontally developed, flat and layered- Cumuliform – vertically developed, puffy- Cirroform – wispy, high in altitude, made of ice crystals- Fog formation - Fog formations is essentially “cloud” formation at or near the Earth’s surface- Fog can form almost the same way as clouds, but two main differences exist. Moisture source – higher amounts of water vapor in cooling areas. Note that clouds generally do not form this way.- Types of fog- Advection fog – when warm, moist air moves over cooler body of water (air in one place migrates to another where conditions are right for saturation) Evaporation (or Steam) fog – cold air lies over warmer body of water, and evaporation from water surface causes saturation and fog Upslope Fog – air cools as it moves upslope… as in our Great Smoky Mountains Valley Fog – air in valleys is denser and colder than surrounding air, causing fog- Radiation fog – loss of longwave radiation at night over moist surface causes saturation. Air masses and Uplift Mechanisms- Source Region – Location from which an air mass originates- Classify air masses by:- Moisture – these can be either maritime (m) = moist or continental (c) = dry- Temperature – these can be Equatorial (E), tropical (T), polar (P), Arctic (A), or Antarctic (AA). cP – continental polar cT – continental tropical cA – continental arctic cAA – continental Antarctic mT – maritime tropical mP – maritime polar- Principal Air Masses of North America- Lake Effect Snow – as air masses migrate form source regions, temperature and moisture characteristics change and take on characteristics of the land over which they pass - Atmospheric Lifting Mechanisms- Convergent Lifting – Air coming together, no place to go but up- Convectional Lifting – uneven heating of the Earth’s surface.- Orographic Lifting – Forcing over a mountain barrier Air forced over mountain on windward slope cools at the Dry Adiabatic Rate Once Ta lowered to Tdp = saturation, condensation at the Lifting Condensation Level = clouds Air continues to rise over mountain, cooling now at the Moist Adiabatic Rate.  Once peak is reached, air then descends the leeward slope, warming at the DAR.  Dry hot leeward winds are called chinook winds.  Large dry area on leeward side of mountains is called the Rainshadow.- Frontal Lifting – Air masses colliding (cold and warm fronts)Frontal Uplift- Front – the leading edge of an attacking air mass- Fronts are named after the attacking air mass- Cold Fronts- Cold air is denser, heavier- Cold air forces warm air aloft- Relatively narrow, but up to 400 km wide- Blue triangles on a weather map- Fast-advancing cold front can cause violent lifting and create a zone right along or slightly ahead of the front called a squall line. - Moisture: cold air mass down- Temperature: cold air mass down- Pressure: cold air mass up- Wind Direction: cold air mass from West – North West- Rainfall: cold front: intense, short- Cloud cover: cirrus, cumulus, then cumulonimbus- Warm fronts- Warm air moves up and over cold air - 1000 km wide - Red or orange half circles on a weather map- Moisture: warm air mass up - Temperature: warm air mass up - Pressure: warm air mass down- Wind Direction: warm air mass from South – South West- Rainfall: warm front: steady, long-lasting- Cloud cover: warm front: cirrus, cirrostratus, altostratus, stratus, nimbostratus- Both cold and warm fronts cause air to be uplifted- This causes adiabatic cooling, low pressure, cloud development, rainfallMidlatitude Cyclones- Lifecycle of Midlatitude Cyclone- Cyclogenesis = Early Stage Process in which Low wave cyclones develop and strengthen- Open Stage To the East of the developing Low system center, warm air begins to advance North As the MC matures, the CC flow draws cold air from North and West and warm air from South- Occluded Stage Cooler cP air mass denser than warmer mT air mass. Cold front speed ~25 mph; warm ~10 mph Thus, cold front overtakes warm front, wedges beneath it, and produces an occluded front Precipitation is moderate to heavy initially, then tapers off as warm air wedge is lifted higher. Stalemate between cooler and warmer air masses and airflow on either side of the front is parallel to the front = stationary front Eventually it moves and dominating air mass results (either cold/warm front)- Dissolving StageExtreme Weather- Thunderstorms- Tornadoes- Speed of air above surface is slower than speed of air well above the ground.- This initiates a spinning motion, much like a rolling barrel.- Encounters strong updrafts associated with thunderstorm activity- Causes shift from horizontal rolling to vertical spinning.- Within the cumulonimbus cloud, a mesocyclone will then form.- Mesocyclone: large, rotating body of air within a thunderstorm- When this happens, a tilted supercell cloud forms that can spawn supercell tornadoes.- Wind speeds increase as the vortex tightens.- Blizzards- Blizzard of 1993- Midlatitude cyclone, began with deep trough of low pressure extending into Gulf of Mexico on March 12- Clash of warm mT air mass with very cold cP air mass, plus mP air mass.- Derecho- Widespread, long-lived, violent, convectively-induced, straight-line windstorm.- Associated with a fast-moving band of severe thunderstorms, usually in late spring and summer. - Sustained winds of 58 mph.- Causes severe damage, extensive forest blowdown.- Tropical Cyclones-