geo - weather processes and phenomena

what is humidity?

the amount of water vapour in the air

what is relative humidity

the amount of water vapour in the air expressed as a % of the max amount of water vapour the air can hold

what is dew point

the atmospheric temp below which water droplets begin to condense and dew can form

what is condensation nuclei

tiny particles in the atmosphere such as dust, pollen smoke or salt on which water capour condenses to form droplets, leading to cloud formation

what is evaporation?

liquid to gas: endothermic

the changing phase of water from a liquid to a vapour with the addition of heat

what is condensation

gas to a liquid - exothermic

when water vapour cools and changes phase from gas to liquid due to cooling and reaching its dew point

what is freezing?

liquid to solid - exothermic

when water changes phase to become a solid due to temp cooling to below its freezing point

what is melting

solid to liquid - endothermic

when a solid changes phase to become a liquid usually with the addition of heat and raises the temp to its melting point

what is deposition?

gas to a solid - endothermic

when a substance in gas form changes phase to become a solid, bypassing the liquid phase and usually happens with rapidly cooler temps below freezing points

what is sublimation?

solid to gas - exothermic

when a gas changes phase to become a gas , bypassing the liquid phase and usually happens with the addition of heat

what is rainfall?

the falling of liquid water droplets when they become too heavy to stay in the air

how does rainfall happen?

evaporation from oceans, lakes and rivers become water vapour

the warm moist air rises and cools at it moves higher

as it cools the vapour condenses into tiny water droplets forming clouds

when the droplets become too heavy they fall due to gravity

what are the 3 types of rainfall

convectional

frontal

orthographic uplift

what is the process of convectional rainfall?

convectional rainfall occurs when the earths surface is intensely heated by the sun, causing warm air to rise, reach its dew point then condense into clouds and lead to heavy rainfall

where is convectional rainfall common in?

tropical and equitorial regions

when does frontal rainfall occur

when two air masses with different temps meet, the warm air rises above the cold air, as it rises it cools and condenses forming clouds.

light rain falls at a warm front, cold air falls at a cold front

where does frontal rainfall occur

at mid latitude regions

UK 55 degrees north

when does orthographic uplift of air rainfall occur

occurs when moise air is forced to rise over a mountain range, cools, condenses and forms precipitation. This process results in a wet side and a dry side of the mountain

where does orthographic uplift occur

in the southern alps, west coast gets 7000mm of rain by cantebury plains remain dry

what is radiation cooling?

the loss of temperature at or near ground surface by outgoing longwave radiation usually at night

how does radiation cooling work?

during the day the Earths surface absorbs solar radiation and warms

at night the surface release this heat in the form of longwave radiation

if the heat radiated away is not replace by clouds, etc the surface temp drops

what are clouds

clouds are an aerosol consisting of a visible mass of tiny liquid droplets or frozen ice crystals suspended in the atmosphere

what is hail?

hail is a form of solid precipitation of pellets or larger of ice

how is hail formed?

inside a thunderstorm the warm air rises quickly and they carry water droplets high into the colder parts of the atmosphere

when these water droplets reach the freezing lvl’s of the cloud they freeze into ice pellets

the pellets get carried by the up draughts and down ones lots of time collecting more layers of ice,

what is snow?

an atmospheric water vapour frozen into ice crystals and falls from the clouds as light white flakes, crystals are aggregeated

what is the process of snow forming

water vapour condenses to form droplets, the droplets freeze into ice crystals ar low temps,(deposisition) updrafts keep the ice crystals aloft and water droplets in the clouds are attracted to the ice crystals (Attaching to them) they become heavy and fall

what is dew

dew is water in the form of droplets that condense on cold surfaces

how does dew form?

during the night, the temp of the ground drops, especially on clear nights

as the air near the ground cools, it can no longer hold as much moisture so when it reaches its dew point it condenses into tiny water droplets

what is fog

condensation at or near the earths surface. it forms when moist air is in contact with the cool ground

what are the two types of fog?

radiation fog and advection fog

what is advection fog

common in costal regions, occurs at anytime.

its caused by the movement of warm air over a cold surface/ the surface cools the air and condensation occurs as the air reaches its dew point

what is radiation fog

occurs at nightime

radiation cooling of the ground caused by clear skies

air near the ground cools and becomes aturated. dew point is reached a