2.3 Weather Processes Flashcards
(15 cards)
Definitions;
Sublimation
Deposition
Sublimation - solid changes state to a gas without going through liquid phase
Deposition - gas turn into a solid - without turning into a liquid state
rime at high altitudes
Factors effecting evaporation
- humidity is low, air is dry
- temperature rise, energy of molecules will be high so more likely to escape bonds
- supply of moisture
Factors effecting condensation
- enough water vapour is evaporated so air becomes saturated (100% humidity)
- when temps drop air can hold less moisture so dew point is reached
- has to be hydroscopic nuclei (dust/smoke/ash) particles
What causes cooling for condensation
Conduction
- when cool air comes into contact with colder earth - so air cools
Radiation Cooling
- when ground is cooled by terrestial radiation (longwave) which escapes through space window
Expansion Cooling (adiabatic cooling)
- air expands and contracts as it moves between heights
- reaches condensation level where air condenses into water
- leads to release of energy
How do clouds form?
- air which contains water vapour is forced to rise
- the rise may be due to; convection, orthographic, collision
- as moisture rises temperature cools which leads water vapour to condense
- moisture will cool to dew point temperature (helped by hydroscopic nuclei)
- the water droplets are kept afloat in the atmosphere as clouds
- water droplets coalesce become larger and overcome force of gravity keeping them up
When will precipitation happen?
- when there is enough moisture
- droplets have to be large enough to fall through rising air currents
How does different precipitation happen?
- Coalescence, 2 water droplets collide and join = rainfall
- aggregation; 2 ice crystals collide form snow
- accretion; ice joins water forms hail
Why do clouds rise?
- Orthographic; mountain ranges or other force clouds to rise leading to banner clouds
- Convectional; Land become very hot, hot air rises bring cloud with it
- Frontal; warm air meets cold air, less dense warm air rises
Formation of Hail?
- water dropleys are mobed through clouds up and down
- freesing occurs on water droplets as temps go down
- frozen water droplets collide w normal ones (accreation)
- once large enough fall
Formation of Snow?
- water droplets are moved up and down in clouds
- leads to freezing of water droplets
- when two frozen droplet come together (aggregation) form snow
- when heavy enough they fall
Formation of Dew?
- No cloud cover; heat is lost rapidly by radiation cooling through space window
- earth’s surface cools rapidly, which cools the air above the ground
- if this air is cooled to the dew point temperature condensation will occur on surface
3 Different types of fog
Radiation
temperature Inversion
Advection
How does temperature Inversion fog form?
- cold temperatures with warm above them
- leads to cooling of the air at the ground to dew point
How does advection fog form?
- warm moist air passes over cooler ocean or land masses
- cooled to dew point
- condenses forms fog
How does radiation fog form?
- Same as dew formation
- air condenses as well as ground
