Geography

Geography

1. Weather refers to the condition of the atmosphere at a particular place and specific time

   • Elements of weather
     • Temperature
       • Factors Affecting temperature
         • Latitude
           • distance from any point of the earth that can be measured north or south of the equator
           • The lower the latitude, when solar angle is high, sun ray's are more concentrated on the are hence higher mean annual temperature. Hence, if solar angle is lower, sun ray is spread out on a wider area, therefore, lower mean annual temperature
         • Altitude
           • Height of place in relation to sea level
             • Main Idea!! General decrease of 6.5 degrees celsius for every 100m increase in altitude
             • R/S : the higher the altitude, the lower the temperature
             • Distance from the sea; Solar energy reaches the earth as shortwave radiation. About 45% of shortwave radiation is directly absorbed by the earth's surface. The earth's surface is heated up and emits long wave radiation. The longwave radiation is absorbed by GHG in the atmosphere and this warms the earth. Air nearer the earth's surface traps more heat than at places with higher altitudes. Therefore the further up you move away from the surface of the earth[ which is heated up by the sun]the temperature decreases
             • Density of air; Air density is a result of gravity. Dense air near the surface is able to trap more heat from longwave radiation therefore has a higher temperature. Less dense air on top of the mountain, has less ability to absorb heat than the other denser air at sea level therefore resulting in lower temperature.
         • Distance from the sea
           • The continents (land) heating and cooling more quickly than oceans, this influences the temperatures of inland and coastal areas
           • The difference in the rate of heating and cooling of land and sea affects the temperature of coastal and inland areas
           • Maritime effect refers to the effect of large ocean bodies have on climate of coastal areas; It occurs at the coastal areas . During summer, air over the sea is cooler than air over land . Sea heats up slower than the land. The cooler air over the sea helps to lower the temperature of coastal areas. During winter, air over the sea remains.Warmer than the land as the sea cools more slowly than the land. The warmer air over the sea increases temperature over the coastal areas. so, cooler summers and warmer winters. This then results in a small annual temperature range . E.g. of some places include Anchorage, Alaska
           • Continental effect refers to the effect of huge land surfaces have on climate of inland areas; It occurs at inland areas. During summer, air over sea is warmer than land. Sea heats up faster than the land. The hotter air over the sea helps to increase the temperature of the coastal areas. During winters, air over the sea remains cooler than air over the land as the sea cools fasterthan the land. The cooler air over the sea decreases temperature over the coastal areas. THis results in warmer summer and cooler winter. this is also due to the fact that the inland areas are located away from the sea so temperature is not influenced by the sea.this results in large annual temperature range. e.g. could be New York and Fairbanks
         • Cloud cover which is the extent of sky covered by the clouds; Higher amount of cloud cover results in smaller daily temperature range.
           • The higher the cloud cover, the lower the temperature in the day
           • Presence of clouds : During the day, clouds reflect large portion of the sun's energy back to space. This then absorbs the heat radiated from the earth's surface. This keeps the earth cool during the day. During the night the clouds absorb more of the heat that is radiated from the earth's surface and prevent it from escaping into space. This keeps the earth warm at night. So the presence of more clouds result in smaller diurnal temperature range.
           • Absence of clouds; during the day, absence of clouds allows large amount of the sun rays to reach the earth. The earth's surface heats up so the air near the earths surface is warmer. During the night, the absence of the clouds allows more of the heat radiated from the earth's surface to escape into space. Thus the air near the surface is thus cooler at night. So the absence of clouds there is a larger diurnal temperature range
     • Rainfall
       • Convectional rain
       • Relief rain
     • Humidity
       • Relative humidity refers to the measurement of the actual amount of water vapour in the air versus the maximum amount of water vapour that the air can hold at a given temperature
         • It is the ratio between actual amount of water vapour present in a mass of air and the maximum amount of water vapour the air can hold at the given temperature
         • The amount of water vapour in the air affects relative humidity. Capacity of air to hold water vapour on its temperature.
         • Saturation occurs when RH reaches 100% The temperature at which saturation occurs is dew point; condensation of water vapour to form clouds. The dew point temperature refers to the condensation from the water vapour to water droplets and eventually form clouds
         • The effect of temperature on relative humidity. As the temperature increases, the air will be able to hold more water vapour. As air molecules are more spread out, more water vapour can fill the spaces. Therefore, assuming the water vapour in the air is constant, relative humidity is lower at higher temperature. At lower temperature the air will not be able to hold as much water vapour. As air molecules contract, less space to hold water vapour. Therefore assuming the actual water vapour is constant, relative humidity is higher at lower temperature
     • Cloud Cover
     • Wind
       • Moving air created when neighbouring locations have different air pressure. Air moves from high to low pressure. the larger the difference in pressure the faster the wind speed
       • Monsoon winds which are seasonal movements of large air masses across the earth as the Northern and Southern Hemisphere experience different season
         • This is due to extreme heating and cooling of large land masses
           • Winds are deflected as they move across the earth due to the Coriolis effect
       • Southwest monsson
       • Northeast Monsoon
     • Pressure
       • Force exerted on a unit area of the earth's surface by the weight of a column of air above it
       • Instrument to use : measured in millibars using a barometer

2. Climate refers to the average condition of the atmosphere of a particular place over a long period of time, usually over 30 years

3. Atmosphere of the earth is the layer of gases, commonly known as air that surrounds the planet Earth and is retained by the Earth's gravity

4. Climate change