Lesson 3 Flashcards
Define humidity
the amount of water vapour in an area, when an air parcel gets to a certain point it will become saturated and condense
Define absolute humidity
total amount of water vapour that a parcel of air can hold, measures as grams of moisture per cubic meter
Define relative humidity
amount of water vapour is a % of what a parcel of air can hold
Define cryospheric processes
processes that affect total masses of ice from small scale to global ice amounts-> direct impact on major water stores, locked up as ice from the hydrosphere-> lowering sea levels
what is evaporation?
energy from solar radiation hits the surface of the water or land-> liquid water to change state, dependent on several factors e.g. amount of solar energy, availability of water, humidity of air
What is transportation?
water transported from roots to leaves-> lost through pores of the leaf surface, leaves intercept rain as it falls, water is evaporated before reaches the soil
What is condensation?
air cools where it is able to hold less vapour-> if it is cooled enough, it will become saturated (dew point temp), excess water in the air condenses on tiny particles e.g. smoke or surfaces that are below dew point temperature
What is fog?
- a could that touches the ground, visible during condensation where molecules of water vapour combine to make tiny liquid water droplets that hang in the air
- happens when air is very humid, must be lots of wv for formation
- dust/pollution needs to be in the air, wv condenses around these microscopic solid particles
what is radiation fog?
- formed by the cooling of land after sunset by infrared thermal radiation, in calm conditions with a clear sky
- the cooling ground then cools adjacent air by conduction, causing the air temperature to fall and reach dew point-> fog
what is advection fog?
occurs when mist, warm air passes over a colder surface and is cooled
- when wind blows in the right direction-> sea fog can become transported over coastal land areas
what is the difference between fog and mist?
- both created by water droplets, differing only in their overall locations and density
- fog=a cloud that touches ground level
- mist= wherever water droplets are suspended by air by temperature inversion, changes in humidity etc
- fog is denser and lasts longer, mist reduces visibility more
what are the 5 steps to cloud formation?
- the sun heats the ground, heating up the air above it
- Convection- the parcel of air starts to rise and expand, if its warmer than surrounding air (absolute instability) it continues to rise
- When there is high pressure, the particles are very close, collide, kinetic energy transferred
- As the parcel is heated by the sun it rises and expands-> pressure cools and particles have the space to move-> collide, kinetic energy reduces (adiabatic cooling)
- decrease in temp and pressure-> water vapour condenses into water droplets that fall to the ground as rain or snow
name the 3 types of rainfall
- frontal rainfall
- relief/orographic rainfall
- convective rainfall
what is frontal rainfall?
- mainly occurs in mid-latitude regions (warm, tropical air meets cold, polar air)
- when these air masses meet-> warm, less dense air is lifted over the cold dense air-> front cools, condense into water vapour-> rainfall= clouds
what is relief rainfall?
mountainous areas close to prevailing westerly winds, more likely to occur than other types
produced when moisture-laden air is forced upwards over high ground-> cloud and potentially precipitation
