weather and climate 1.3 Flashcards
how does the type of soil affect the rate of water movement above and below the earth’s surface? [2 points]
infiltration rates and groundwater flows are faster in soil which has larger pores (e.g. sandy soil) than in soil which has smaller pores (e.g. clayey soil).
larger pores allow more water to infiltrate, allowing the water to move up more quickly
how does surface runoff speed affect infiltration speed?
surface runoff speed is inversely proportionate to infiltration speed.
what is dew point temperature?
dew point temperature is the temperature when the atmosphere reaches 100% relative humidity.
what is saturation?
air is at 100% r.h.. air carries the maximum amount of water vapour it can hold at that temperature (dew point temperature)
what is relative humidity?
r.h. refers to the ratio of the amount of water vapour is in the air to the maximum amount of water vapour the air can hold at a given temperature.
r.h.:
actual amount of water vapour present in the air (g/m^3)
—————————————————-
maximum amount of water vapour air can hold (g/m^3)
x 100%
what is the relationship between relative humidity and temperature?
when temperature increases, the amount of water vapour that air can hold increases. r.h. therefore decreases.
r.h. is at 100% when air holds the maximum amount of water vapour. air is now saturated.
when r.h. exceeds 100%, condensation occurs. This may occur when more water vapour is being added to the air through evaporation OR air temperature drops.
hence, r.h. and temperature have an inverse relationship.
how are clouds formed? [3 points]
at higher temperatures, air expands and can hold more water vapour.
at dew point temperature, the air condenses into water droplets on condensation nuclei.
these particles provide the surface that water vapour needs in order for condensation to occur.
how is rain formed? [3 points]
water droplets in the clouds collide and coalesce, becoming bigger and heavier.
once they are large and heavy enough, they fall on the earth as raindrops/precipitation.
sometimes, these droplets break apart as they fall.
how is convectional rain formed?
[3 points]
in the day, heat from the sun is absorbed by the land, and the air above it gains heat.
the warm air rises and cools, and condenses on condensation nuclei at dew point temperature. clouds are formed. (cumulonimbus clouds)
water droplets in the clouds collide and coalesce, and when they become large and heavy enough, they fall on the earth as rain.
how is relief rain formed?
prevailing winds pick up moisture over the sea, and push the moist air up the windward side of a mountain.
the rising moist air cools and condenses on condensation nuclei at dew point temperature. clouds are formed.
water droplets in the clouds collide and coalesce, and when they become large and heavy enough, they fall on the earth as rain on the windward side.
as most of the moisture has fallen on the windward side, the leeward side experiences dry descending air and is thus dry.
what are the conditions for relief rain to occur? [1 point]
relief rain will not occur if the terrain is not high enough. convectional rain will occur.
what is coalescence? [1 point]
the process by which water droplets or ice crystals grow in size as they combine with other droplets.
what is prevailing wind? [1 point]
wind blowing from the dominant wind direction
what is the windward side? [1 point]
the side of the mountain where warm, moist air rises and precipitation falls on.
what is the leeward side? [1 point]
the side of the mountain where the air is dry and no rain falls.
