1. Atmosphere, Weather and Climate

2. Structure of Earth’s Atmosphere
A layer of air which surrounds the Earth
It is held in place by the pull of Earth’s gravitional forces
Earth’s gravity is strongest nearer to the surface, therefore, most of the atmosphere is found near the surface.
Consists mostly of:
Nitrogen
Oxygen
Water vapour
Dust particles

3. Other gases (carbon dioxide, water vapour) 1%
The Atmosphere (cont’d)
Other gases (carbon dioxide, water vapour) 1%
Nitrogen 78%
Oxygen 21%

4. Upper part of the atmosphere contains little atmospheric water vapour and other gases and experiences no changes in weather.
Troposphere contains most atmospheric water vapour, other gases and dust and experiences weather changes

5. Importance of the Atmosphere
Helps sustain life
Protects the Earth

6. Weather and Climate Weather
The Sun’s rays heat up the Earth’s land and sea surfaces
Heat reflected from these surfaces warm up the air above
Hot air rises and causes condition of the atmosphere to change

7. Weather VS Climate

8. Weather and Climate (cont’d)
When this happens, we experience a change in weather
Meteorologists define ‘weather’ as the condition of the atmosphere at a particular place over a short period of time

9. Weather and Climate (cont’d)
Weather pattern of a place over a long period of time, usually 30 years
The basic elements of weather and climate:
Sunshine
Temperature
Humidity
Clouds
Rainfall
Air pressure
Wind

10. How Weather and Climate Affect People
Weather affects our daily life
Climate affects how people live generally
Where people choose to live
Types of houses people live in
Climate affects food and water supply

11. Measuring Temperature

12. Daily Maximum and Minimum Temperatures
Daily maximum temperature: the highest temperature reading for the day
Daily minimum temperature: the lowest temperature reading for the day

13. Maximum and Minimum Thermometers
Maximum temperature is measured by the maximum thermometer
It consists of a glass tube containing mercury and a metal index
When temperature rises, the mercury expands and pushes the metal index upwards
When temperature falls and the mercury contracts, the metal index stays in place
The minimum thermometer works in the same way, but contains alcohol instead of mercury

15. Where to Place Thermometers
Instruments used to measure temperature are usually placed in a Stevenson Screen
A raised white wooden box with louvres
Shelters the instruments from the direct heat of the Sun
Allows air to flow freely through it
Avoids heat radiating from the ground

17. Mean Daily Temperature
The average temperature of a place on any one day
Daily recording of this temperature reveals a pattern which provides a more accurate picture of the climate of the place

18. Mean Daily Temperature (cont’d)
Formula for calculating mean daily temperature
Daily maximum temperature +
Daily minimum temperature
Mean
daily
temperature = 2

19. Mean Daily Temperature (cont’d)
Mean daily temperature for Singapore
Daily maximum temperature is often 32 degrees Celsius
Daily minimum temperature is often 25 degrees Celsius
Mean daily temperature =
( )OC 2
28.5OC =

20. Diurnal Temperature Range
Shows how extreme temperatures can get within a day
Used for describing the climate of a place
Formula:
Diurnal
Temperature
range =
Daily
maximum
temperature
Daily
minimum
temperature -

21. Diurnal Temperature Range (cont’d)
Diurnal temperature range for Singapore
= ( )OC
= 7OC