Weather and Climate KQ1 Flashcards
6 elements of weather
1) Temperature
2) Relative Humidity
3) Clouds
4) Rainfall
5) Air Pressure
6) Wind
Temperature
- Degree of hotness/coldness at a place
- High temps >20c, low temps <10c
- Small Temp range <5c, large temp range >15c
Factors affecting Temperature
CLAD
- Cloud cover
- Latitude
- Altitude
- Distance from sea
TF: Cloud cover
Def: Extent sky is covered by clouds
-More cloud cover = smaller diurnal temp range
TF: Latitude (Most important factor affecting temp)
Def: Distance of any point on earth measured North/South from equator
-The further away from the equator, the lower the temp.
1) Solar Angle
- High Latitude = low solar angle = sun rays more dispersed = lower temp
- Lower Latitudes = higher solar angle = sun rays more concentrated = higher temp
2) Distance from sun
- Closer to equator = shorter distance from sun = less sun ray energy dissipated to space = warmer temp
- Further from equator = further distance from sun = more energy loss to space = cooler temp
-As latitude increases, mean annual temp decreases
TF: Altitude
- Height of place in relation to the mean sea level
- Lapse rate: 6.5c every 1000m
1) Distance from earths surface
- Shortwave radiation heats earths surface, re-emitted to atmosphere as longwave radiation
- Higher altitude = further distance from earths surface = lower temp.
2) Greenhouse gases
- Longwave radiation trapped by GHGs,
- GHGs near earths surface trap more heat
- Higher altitudes = less heated GHGs = lower temp
3) Air Densities
- Higher altitude = less dense air
- Denser air absorbs more heat from longwave radiation emitted from earths surface, temp increases
- Higher altitudes = less dense air = less heat absorbed = lower temperature
TF: Distance from sea
- Sea has higher specific heat capacity compared to land
- Difference in rate of heating and cooling of sea and land affect temp of coastal and inland areas.
1) Maritime effect
- Effect large ocean bodies have on coastal climates
- Small annual temp range,
- Cooler summers, warmer winters
Summer:
- Air over sea cooler than air over land,
- land heats up quickly, sea heats up slowly,
- Cooler air over seas cool coastal regions
- Coastal areas cooler than inland areas
Winter:
- Air over sea remains warmer,
- Land cools quickly, sea cools slowly
- Warmer air over sea warms coastal areas
- Inland areas cool faster than coastal areas
- Coastal areas warmer than inland areas
2) Continental effect
- Effect continental surface has on climate of inland areas
- Large annual temp range
- Temperatures not influenced by sea
- Warmer summers and cooler winters inland.
Relative Humidity
- Ratio between actual amount of water vapour present in the air and maximum amount of water vapour the air could hold at a given temperature
- Varies with temperature
- Warm temp holds more than cool temp. (Air molecules more spread out, assuming water vapour is constant, warm air has lower saturation)
-As temperature increases, relative humidity decreases
Clouds
Formation:
1) Earths surface heated, water evaporates to water vapour
2) Vapour rises, cools
3) Air becomes more humid
4) Saturates when dew point is reached
5) Condensation occurs if condensation nuclei present
6) Condensed droplets merge and become larger (Coalesence)
7) Suspended as a visible mass of water droplets in atmosphere
8) Clouds grow and fall as precipitate
Rainfall
- Precipitation: Anything which falls from the sky
- High rainfall: >1500mm, low rainfall: <250mm (annually)
- Result of air instability
> Convectional rainfall
- Occurs when earth surface heated intensely
- Common in tropics ( Large amounts of sunlight)
1) Sun rays heat up earth surface
2) Heated air less stable, expands and rises
3) Rising air cools and reaches dew point, condensing and forming clouds.
4) Fall as short intense rainfall
> Relief rain
- Occurs when warm, moist air is forced to rise over landforms such as mountain ranges
- Criteria: Large landforms, prevailing winds, large water bodies.
1) Prevailing winds pass moist air over the sea and arrives at the coast
2) Air is forced to rise as it encounters highlands, reaches dewpoint quickly and condenses into clouds
3) When water droplets are large and heavy enough, rain falls on windward side of landform
4) Results in leeward side to be dry since most of moisture would have fallen on the windward side
Pressure
- Force exerted per unit area of earths surface by the weight of a column of air above it.
- High pressure: >1,013mb (above atm), low pressure: < 1,013mb (below atm)
- Pressure varies with temp.
- Warm air expands, becomes less dense, rises = low pressure
- Cool air contracts, becomes denser, sinks = higher pressure
Winds
- Air moving from an area of high pressure to an area of low pressure
- Pressure gradient: Difference in air pressure between 2 locations
- The greater the pressure gradient, the faster the wind speed
- Wind speed: Rate at which air is moving (Anemometer)
- Wind direction: Direction from which wind blows (Wind Vane)
- Wind frequency: Percentage of time wind blows from a particular direction, (Wind rose)
- Most frequent wind direction known as prevailing wind direction
Local Wind systems
- Lower day temp, regulate night temp
- Result in smaller diurnal temp range
> Land Breeze
1) Wind that blows from land to sea
2) At night, land cools faster than sea, cool air sinks over land
3) Air pressure over land is higher than the sea
4) Air moves from an area of high pressure to area of lower pressure, wind blows from land to sea.
> Sea breeze
1) Breeze that blows from sea to land
2) During the day, land heats up faster than the sea, resulting an a region of higher pressure over the sea
3) Since air moves from a region of higher pressure to a region of lower pressure, wind blows from the sea to the land.
June to September
-Summer in Central Asia, winter in Austrailia
- South-West Monsoon
- Summer northern hemisphere and winter in southern hemisphere
October to February
- Summer in Australia, Winter in Central Asia
- Northeast Monsoon
- Summer in Southern Hemisphere, Winter in Northern Hemisphere
