1. What is weather and climate?
1. Weather
a) state of atmospheric conditions at a particular time and place
b) described using variables including air temperature, cloud cover, precipitation, wind speed and wind direction
2. Climate
a) average state of atmospheric conditions over a specified time period
b) climate types include tropical equatorial climate, tropical monsoon climate and cool temperate climate
3. Climatic hazards
a) changes in climate and extreme weather including heat waves, droughts, floods, cyclones and wildfires
b) impact natural and human systems significantly
2. Why does air temperature vary across Earth’s surface?
1. Earth’s rotation and revolution
a) Earth’s rotation on its axis results in variability of air temperature over time in a day
b) Earth’s revolution around the sun results in variability of air temperature over time in a year
2. Latitude and altitude
a) at the global scale, solar angles are lower at higher latitudes resulting in lower air temperatures
b) at a local scale, air pressure is lower at higher altitudes resulting in lower air temperatures
3. Nature of surfaces and distance from sea
a) earth surfaces including snow cover, vegetation and exposed soil affect site specific air temperatures
b) maritime effect on coastal areas and continental effect on inland areas affect site specific air temperatures
3. Why does precipitation vary across Earth’s surface?
1. Water cycle
a) movement of water between the atmosphere and the Earth’s surface through evapotranspiration, condensation and precipitation
b) movement of water at different rates in the form of infiltration, surface runoff and groundwater flow
2. Relative humidity
a) condensation is affected by the amount of water vapour in the atmosphere
b) condensation occurs when the amount of water vapour exceeds the amount that can be held by the atmosphere at a given temperature
3. Clouds and precipitation
a) clouds form due to condensation nuclei and the coalescence of water droplets in the atmosphere
b) results in precipitation including convectional and relief rainfall
4. Why does wind direction and wind speed vary across Earth’s surface?
1. Unequal distribution of air temperature
a) results in uneven distribution of pressure gradient
b) initiates horizontal motion of air and determines wind direction
2. Wind speed
a) influenced by strength of pressure gradient between two places
b) and friction due to Earth’s topography
3. Local and regional winds
a) land and sea breezes occur on a local scale
b) Northeast and Southwest monsoons occur on a regional scale and are influenced by the Coriolis force
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