geog book 3 chap 1 Flashcards
what is weather?
state of atmosphere at a particular place and time described using variables - air temp, cloud cover, precipitation, wind speed, wind direction
what is climate
average state of the atmosphere at a particular place over a long period of time, typically 30 years
what are the characteristics of tropical equatorial climate
generally high temperatures all year round (27 deg C)
small annual temp range (~2-3 deg C)
high annual precipitation(>2000mm) that falls evenly throughout the year
between 10 deg N and 10 deg S of the equator
what are the characteristics of tropical monsoon climate
generally high temperatures all year round (~25 deg C)
small annual temp range (~3-4 deg C)
high annual precipitation(~1500mm)
distinct wet and dry seasons
between 5 deg N/S and 30 deg N/S of the equator
what are the characteristics of cool termperate climate
4 distinct seasons - spring summer autumn winter
large annual temp range (~21 deg C)
annual precipitation (300-900mm) that falls evenly throughout the year
between 45 N/S and 60 N/S
what does a climograph show
avg monthly temp (deg C) and precipitation (mm)
how does climate change cause climatic hazards?
climate change causes weather patterns to be unpredictable, more extreme, and more frequent, causing negative impacts to natural and human systems
how does air temperature vary across time in a day
due to the Earth’s rotation on its own axis, one complete rotation is 24h
as the earth rotates, the sides of the earth that face the sun experiences day and receives solar radiation and experiences a high temperature
as the earth continues rotating, that side will face away from the sun and experiences night time where it does not receive solar radiation and thus experiences lower temperatures
how does the air temperature vary at midday?
sun is directly overhead
due to earth’s spherical shape, solar radiation is spread over a smaller area
solar radiation is more concentrated
temperature is the highest in the day
how does the air temperature vary before and after midday?
sun is not directly overhead
due to the earth’s spherical shape, solar radiation is spread over a larger area
solar radiation is concentrated
temperature is lower than midday
how does the air temperature vary before sunrise?
place does not receive solar radiation and loses heat in the form of longwave radiation
temperature is at its lowest before sunrise as the place has lost heat over the longest period of time
how does the temperature vary over time in a year? - June
northern hemisphere leans more towards the sun and receives more direct solar radiation and high temperature
southern hemisphere leans away from the sun and receives less direct solar radiation and lower temperatures
how does the temperature vary over time in a year? - December
northern hemisphere leans away from the sun and receives less direct solar radiation from and lower temperatures
southern hemisphere leans more towards the sun and receives more direct solar radiation and higher temperatures
how does the temperature vary over time in a year? - March and September
neither hemisphere leans towards the sun thus both experience moderate temperatures
northern hemisphere experiences spring in march and autumn in september
southern hemisphere experiences autumn in march and spring in september
how does the temperature vary over time in a year in the tropics?
tropics, located close to the equator receives direct and near-direct solar radiation throughout the year
and thus experiences high temperatures throughout the year
how does latitude cause variations in air temperature across places
temperatures are lower at high latitudes
due to the Earth’s spherical shape, solar angle varies at different parts of the Earth
increasing latitude means a smaller solar angle causing solar radiation is less direct and spread over a large area and is less concentrated, lowering temperatures
how does altitude cause variations in air temperature across places
the higher the altitude the lower the temperature
at higher altitudes, air is less dense and there is lesser air pressure as gravity pulls most air molecules towards the ground surface
with fewer air molecules, air has a lower ability to absorb and radiate heat decreasing the temperature
how does type of surface affect air temperature at specific sites? - dark coloured surfaces
dark surfaces generally absorb higher amounts of solar radiation and radiate more heat increasing temperature at a place
how does type of surface affect air temperature at specific sites? - light coloured surfaces
light coloured surfaces generally reflect more solar radiation and radiate less heat decreasing temperature
how does type of surface affect air temperature at specific sites? - urban vs rural areas
urban areas tend to have high temperatures compared to rural areas as there are a larger area of dark surfaces which absorb more solar radiation and radiate more heat than forests and water bodies
glass-covered buildings reflect sunlight to the ground surface increasing absorption of solar and heat radiation by ground surfaces
how does distance from the sea affect air temperature at specific sites? - coastal areas
due to maritime effect coastal areas experience cooler summers and warmer winters
have a lower annual temperature
this is because the sea heats up and cools down faster than land
during winter the sea is warmer than land warming the air along coastal floods
during the summer the sea is cooler than land and cools the air along coastal areas
how does distance from the sea affect air temperature at specific sites? - inland areas
due to continental effect, inland areas experience warmer summers and cooler winters
annual temp range is high
what are the 6 steps of the water cycle
- water vapour enters atmosphere through evapo-transpiration, suns heat causes water from water bodies to evaporate forming water vapour & plants give out water vapour through transpiration
- as water vapour rises, it cools and condenses into tiny water droplets at dew point temperatures and clouds are formed
- when water droplets in the clouds become big and heavy enough and fall to the ground as precipitation
- water on the ground surface infiltrates subsurface soil and rock
- water flows over ground surface run off and enters water body
- below the Earth’s surface water moves horizontally above impermeable rocks as groundwater flows
how does the type of soil affect the way water moves on and below the earth’s surface
infiltration and groundwater flows are faster in soil which has larger pores than soil with smaller pores
this is because larger pores allow more water to infiltrate and water moves more quickly
how does how built up an area is affect the way water moves on and below the earth’s surface
infiltration rate decreases in built up areas as ground surfaces have tiny pores
speed and surface runoff is faster on smoother gound surface in built up areas as there are decreased obstructions and decreased friction
how does the presence of natural vegetation affect the way water moves on and below the earth’s surface
infiltration rate and groundwater flows are faster at places with vegetation as roots of plants loosen the soil making more open spaces in soil for water to pass through
speed of surface runoff decreases on vegetated areas as stems and roots of grass and plants act as barriers and the increase the surface roughness
what is the formula to calculate relative humidity
actl amt of wv present in air (g/m³)
/ max amt of wv the air can hold (g/m³)
x 100%
how does temperature affect the relative humidity of a place at a specific time
when the temperature increases the amount of water vapour the air can hold increases decreasing relative humidity
relative humidity is at 100% when air holds the max amount if wv as air is saturated
when relative humidity is above 100%, condensation occurs when more wv is added to air througu evaporation and air temperature drops
how are clouds formed?
air rises up in the atmosphere as it cools and reducing the amount if water vapoure it can hold
eventually, the amt of wv exceeds the max amt of wv can hold
at the dew point temperature, air condenses into water droplets on condensation nuclei and provides surfaces where water vapour can change into water droplets into clouds
how is rain formed?
water droplets in clouds collide and coalesce and become bigger and heavier
once wd are large enough they fall to the earth as raindrops
how is convectional rain formed?
- in the day, heat from the sun is absorbed by the land and air above it gains heat
- warm air rises and cools and condenses on condensation nuclei at dew point temperature forming clouds
- wd in clouds collide and coalesce when they become large and heavy enough and fall to the ground as rain
how is relief rain formed?
- prevailing winds pick up moisture over the sea and push moist air the windward side of the mountain
- rising moist air cool and condense on condensation nuclei at dew point temperature and clouds are formed
- wv in clouds collide and coalesce and when they become large and heavy enough there is rain on the windward side
- as most of the moisture has fallen on the windward side and leeward side experiences dry descending air causing the leeward side to be dry
what is the definition of wind
horizontal movement of air across the earths surface, occurs due to unequal distribution of pressure gradients
how is wind formed?
there is an increase in air temperature causing it to be heated, air become less dense and rises. there is a a void and a decrease in atmospheric pressure
decrease in air temperature causing air to cool, becomes denser and sinks increasing the atmospheric pressure
air moves from the area of high pressure to the area of low pressure to fill the void forming wind
how does strength of pressure gradients determine wind speeds
a smaller pressure gradient means a smaller difference in pressure between 2 areas causing slower wind speeds
a high pressure gradient means a bigger difference in pressure between 2 areas causing faster wind speeds
how does friction determine wind speeds
as moving air comes in contact with variations in the earth’s topography, it experiences frictional drag and slower wind speeds
when is the effect of frictional drag the greatest?
when there is uneven relief and rough surfaces on land
explain the formation of land breeze
- in the night, the sea and land lose heat through longwave radiation
- the sea and the air above it lose heat slowly. the warmer air is less dense and rises forming lower pressure over the sea
- the land and the air above it lose heat quickly. the cooler air is denser and sinks forming high pressure over land
- air moves from an area of higher pressure over the land to lower pressure over the sea forming the land breeze
explain the formation of sea breeze
- in the day heat from the sun is absorbed by both the land and the sea through shortwave radiation
- the land and the air above it gain heat quickly. the warmer air is forming lower pressure over the land
- the sea and the air above it gain heat slowly. the cooler air is denser and sinks forming higher pressure over the sea
- air moves from an area of higher pressure over the sea to lower pressure over the land forming the sea breeze
explain the formation of northeast monsoon
from october to february the northern hemisphere experiences winter and cooler temperatures and the southern hemisphere experiences summer and higher temperatures
in winter the air over central asia is cold and thus an area of high pressure
in summer, air over australia is warm and thus an area of low pressure
air moves from central asia to australia
in the northern hemisphere wind is deflected to the right forming the northeast monsoon
the northeast monsoon is dry and cool as less moisture is picked up from central asia, bringing less rain to india
winds blow over the south china sea picking up moisture in the form of water vapour bringing heavy rain to places such as singapore
winds cross over to the southern hemisphere, deflect to the left and pick up moisture over the indian ocean bringing rain to countries like indonesia and australia
explain the formation of southwest monsoon
from june to september the northern hemisphere experiences summer and high temperatures and the southern hemisphere experiences winter and cooler temperatures
in summer, air over central asia is warm thus an area of low pressure
in winter, air over australia is cold thus an area of high pressure
air moves to australia towards central asia
winds cross northern hemisphere and they are reflected to the right and the southwest monsoon is experienced by countries such as singapore malaysia and india
as winds move over the indian ocean it picks up moisture bringing heavy rain to india
