Weather phenomena associated with local energy budgets mist fog dew temperature inversions land and sea breezes At the end of our third lesson on this subtopic I will know the three states in which moisture can be found in the atmosphere and understand the terms condensation evapora ID: 773645
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Weather phenomena associated with local energy budgets (mist, fog, dew, temperature inversions, land and sea breezes ).
At the end of our third lesson on this sub-topic; I will know the three states in which moisture can be found in the atmosphere and understand the terms condensation, evaporation, sublimation, freezing and melting I will be able to explain the formation of weather phenomena associated with local energy budgets (mist, fog, dew, temperature inversions, land and sea breezes)
Fog and Cloud formation: How does air become saturated? North Sea Fog – a coloured visible satellite image
Dew, Frost, Haze and Fog Dew : Common on vegetation early morning after a clear night. (b) Happens on clear nights because surface radiates heat and this is not trapped by a cloud cover. (c) Dew forms on vegetation because it cools more quickly than (say) a road surface; vegetation has a lower heat capacity per unit area. Dew formation releases latent heat, and this reduces the rate at which the surface cools. Therefore the dew point temperature is often the minimum night-time temperature. (a) How? Air is cooled to dew point and becomes saturated.
Frost 1 : Forms if dew point is below 0 ° C. This is now called the frost point. (a) White frost (or hoar frost) forms by ice deposition directly from the vapour , in the form of 6-sided crystals.
(iii) Haze : Dry haze is caused by particulate nuclei, which scatter light like the blue of the sky, and when there is some water deposition, the haze thickens and becomes wet haze. Frost 2: Black frost (or black ice) forms when the dew point is just above 0 ° C so the dew forms first and subsequently freezes as temperature drops below 0°C. A layer of ice is formed without the creation of small crystallites.
FOG – defined when visibility < 1000m Fog is equivalent to a cloud at the surface. Fog forms in one of three ways: by cooling the air by evaporation of water into the air by mixing of two air masses such that when combined, the mixture is saturated The types of fog are named with reference to the method by which the air becomes saturated. Haze: Dry haze is caused by particulate nuclei, which scatter light like the blue of the sky, and when there is some water deposition, the haze thickens and becomes wet haze.
ADVECTION FOG - air is cooled to saturation by having warm moist air moving over a cold surface.. San Francisco has a lot of advection fog since the surface water near the coast is much colder than the water farther off shore. Warm moist air from the Pacific Ocean is advected over the cold coastal waters, chilling the advected air from below.
UPSLOPE FOG - forms as moist air flows up an elevated plain, hill or mountain. As the air ascends, it expands, cools adiabatically (same as any ascending air), and saturates.
Orographic uplift Lee Wave clouds rotor or Lenticular clouds
As species: lenticularis
STEAM FOG - forms when cold air moves over warm water (e.g. heated outside swimming pool) water evaporates from the pool into the air, increasing the dew point and if mixing is sufficient the air above becomes saturated. The colder air directly above the water is heated from below and rises forming what appears to be steam.
RADIATION (GROUND) FOG - produced by the radiative cooling at the surface - common over land in late autumn and winter. - also form in low-lying areas. Favourable conditions: clear (cloud-free) nights (cold), shallow layer of moist air near the ground (e.g. recent rainfall, or near water body), 3. long nights, 4. light winds Radiation cooling takes place from the top of the fog layer; mixing continues in the fog layer, further cooling the ground surface.
VALLEY FOG . Cold air and high moisture content in river valleys make them susceptible to radiation fog. Radiation fogs form at the ground and are deepest around sunrise - sometimes an increase in thickness at sunrise due to the evaporation of dew supplying moisture to the fog
3 methods of cloud formation: 1. Cool air directly 2. Mix with colder air 3. Reduce pressure (adiabatic expansion and cooling) The rapid drop in pressure above an aircraft wing can result in sufficient adiabatic cooling to cause saturation
Eddies - Big and Small Eddy – a circulation formed downwind from an object (examples?) Rotor – rotation formed downwind from a mountain waveWind shear – change of wind speed or direction with height
Sea and Land Breezes Types of thermal circulations Sea breeze (scale of motion?)Land breezeSea breeze front – leading edge of the sea breeze Florida sea breezes can have huge walls of clouds. Make for great gliding due to vertical movement
Sea and Land Breezes
http://oceanservice.noaa.gov/education/pd/oceans_weather_climate/media/sea_and_land_breeze.swf