Chapter 3 Variable Weather and Changing Climate - A Continuing Challenge

GATEWAY 1: Why do different places experience different weather and climate? What is the difference between weather and climate? Weather Climate ● The specific conditions of the atmosphere of a particular place and time ● Shows the short term conditions of the atmosphere. ● Varies from time to time and place to place ○ For example, Singapore on 1st May 2016 at 10 am, hot and sunny but at 4pm raining heavily. ● The average weather conditions of the atmosphere over a long period of time, at least 30 years. ● Climate is what people expect to experience year after year. ○ Places with high temperatures and high rainfall experiences hot wet climate. ○ A place with high temperature in summer and low temperature in winter experiences temperate climate. Elements of weather ● Temperature ​ which is measured with a thermometer. ● Relative humidity ​ which is measured using a sling psychrometer and a relative humidity table. ● Clouds ​ which are measured with your eyes, obviously. ● Rainfall ​ which is measured using a rain gauge. ● Air pressure ​ which is measured using a barometer. ● Wind ​ which is measured using an anemometer. Temperature ● Temperature ​ is the degree of heat or coldness of a place. ● It is measured in ​ Celsius or Fahrenheit ​ scale. ● It is measured using an ​ analogue or digital thermometer, ​ although a ​ maximum and minimum thermometer ​ can be used too. Temperature calculation ● Mean daily temperature ​ is the sum of hourly temperatures divided by 24 hours. ● Diurnal temperature range ​ is the difference between maximum and minimum temperatures recorded in a day. ○ Maximum daily temperature - Minimum daily temperature ● Mean monthly temperature ​ is the average of the daily temperatures in a month ● Mean annual temperature ​ is the average of the monthly temperatures recorded in a year ● Annual temperature range ​ is the difference between maximum and minimum mean monthly temperatures recorded in a year. Factors affecting temperature ● Latitude (Angle of Incidence) ○ Latitude is the distance of any point on the earth measured north or south of the equator. ○ Nearer to the equator, the angle of incidence is higher/vertical and the sun rays are more vertical. ○ This causes solar energy to be concentrated into a smaller area and thus, the temperature will be higher. ○ The opposite is true for areas further away from the equator, causing those areas to have a lower temperature. ● Latitude (Curvature of the Earth) ○ At lower latitudes because of the curved shape of the earth’s surface, the sun rays travel through a shorter distance in the atmosphere. ○ There is less solar radiation lost by reflection, scattering and absorption. ○ Thus places near equator will have higher temperatures as less energy is lost to these processes. ● Altitude (Distance from the surface) ○ The sun emits short wave radiation which is absorbed by the earth’s various surfaces and then re-emitted as longwave radiation. ○ The higher up in the atmosphere you go, the further you are from the majority of the surface of the earth which is being heated by the sun. ○ Therefore, temperature decreases with increasing altitude. ● Altitude (Amount of Particles) ○ The sun emits short wave radiation which is absorbed by the earth and then re-emitted as longwave radiation. ○ With increasing altitude or elevation, air becomes less dense and hence contains less dust and water vapour. ○ Heat from the earth's surface thus escapes more rapidly, thereby lowering the air temperature. ○ In general, air temperature decreases with increasing altitude at a rate of about 0.6°C to 0.65°C per 100 metres (or 6°C to 6.5°C per 1000 m) in a free atmosphere. ○ This change of temperature gradient is called the normal lapse rate (or vertical lapse rate). ○ Examples would be Kota Kinabalu vs. Mt. Kinabalu. ■ Kota Kinabalu is only 200m above sea-level and its temperature ranges from 24 degrees in the night to 33 degrees in the day. ■ Mt. Kinabalu which is 3300m above sea-level and its temperature drops below freezing sometimes. Notes by some weirdo called Conrad Soon. I don’t guarantee the full accuracy of the information here. Special thanks to Mrs Wong, the most wholesome and pure Geography ahma.

■ However, these two areas are of similar latitudes so it shows how altitudes cause temperature differences. ● Distance from the Sea ○ Coastal location (Maritime effect) ■ Maritime effect is the effect that large ocean bodies have on the climate of coastal areas. ■ During summer, as the sea heats up slower than the land, the air over the sea is cooler than the air over the land, causing winds from the sea to have the added effect of cooling down coastal areas. ■ Likewise, during winter as the sea loses heat slower than the land, the air over the sea is warmer than the air over the land, causing winds from the sea to have the effect of warming up coastal areas. ■ This causes a smaller annual temperature range, characterised by milder seasons. ○ Inland location (Continental effect) ■ Inland regions situated at a great distance from the sea have hotter summers and colder winters than coastal regions. ■ The annual range of temperature in inland regions is greater, and the climate is thus more extreme than that of coastal areas ■ This is because the temperatures of these areas are not influenced by the sea. ● Cloud Cover ○ Presence of clouds ■ During the day, clouds help increase the albedo of the area, increasing amount of solar energy reflected back into space. ■ This keeps the earth’s surface cool as it reduces the amount of solar energy the ground receives, thereby reducing temperatures during the day. ■ During the night, clouds help absorb longwave radiation emitted from the earth’s surface, preventing it from escaping into space. ■ This keeps the earth’s surface warm at night as not as much thermal energy is lost into space, increasing temperatures during the day. ■ This results in a lower daily temperature range. ○ Absence of clouds ■ During the day, there are no clouds to help reflect solar radiation back into space, thus the earth’s surface receives the full amount of solar energy. ■ This increases the amount of insolation the earth’s surface receives relative to when there were clouds present, causing the temperatures to be relatively higher during the day. ■ During the night, there are no clouds to absorb the longwave radiation emitted from the earth’s surface, causing more energy to be lost into space. ■ This causes the earth’s surface to lose heat more rapidly, causing temperatures during the night to be relatively lower. ■ This results in a higher daily temperature range. Relative humidity ● Humidity ​ is the amount of water vapour present in the air. ● Relative humidity ​ is the proportion of water vapour present in the air in relation to the maximum amount that air can hold at a particular temperature. ● Saturation ​ occurs when relative humidity is at 100 per cent, causing ​ condensation. ● Dew point ​ is the temperature at which saturation is reached. Factors affecting relative humidity ● Temperature ○ The air parcel gets warmer and expands. ○ This means that it can hold more water. ○ It continues to expand and hold more moisture until it reaches saturation, where the air cannot absorb any more water vapour. ● Moisture available ○ The amount moisture available in an area affects the amount of water that can evaporate into the air. ● Onshore winds ○ Winds coming from the sea carry lots of moisture due to having travelled across an open body of water. Clouds ● A ​ cloud ​ is a visible mass of water droplets or ice crystals that are suspended in the atmosphere. Rainfall ● Precipitation ​ refers to water i