1. Investigating Weather – 17min

2. Weather
Weather is the condition of Earth’s atmosphere at a particular time and place.
Short-term: Hours and days
Localized: Town, Region or State
Sunny
Rain showers
Snow
Tornadoes
Hurricanes

3. Causes of Weather
The movement or transfer of thermal energy, heat, in Earth’s atmosphere that influences:
Temperature
Air Pressure
Wind
Humidity

4. Temperature
The measure of the average kinetic energy of the molecules that make up a substance.
Faster the moving molecules = more kinetic energy = higher temperature
Slower the moving molecules = less kinetic energy = lower temperature

5. Temperature
Air molecules have mass and occupy space, volume = density.
Colder air:
Particle Speed = slower molecule speed
Volume = lower volume
Density = increased density
Cold air sinks!
Warmer air:
Particle Speed = faster molecule speed
Volume = increased volume
Density = decreased density.
Hot air rises!
Convection

6. Temperature Temperature can be affected by several factors:
Earth’s rotation
Earth’s tilt and revolution
Latitude
Altitude
Cloud Thickness
Surface Color and Texture
Proximity to Water

7. Factors Affecting Temperature
Earth’s rotation
Earth rotates, spins, once in 24 hours.
Half of earth is facing the sun - Day
Warmer temperatures - energy received by solar radiation.
Half of earth is facing away from the sun - Night
Cooler temperatures
Night Day

8. Factors Affecting Temperature
Earth’s tilt and Revolution
Earth’s axis is tilted at 23.5 off perpendicular.
Earth revolves, orbits, once around the sun in 365 days (1 year)
Causes different amounts of sunlight to be absorbed or scattered during different seasons.

9. Factors Affecting Temperature
3. Latitude
The distance North or South of the equator affects the amount of solar radiation an area receives – insolation.
Equator receives direct sunlight year-round.
Temperatures are consistently.
Poles receive varying amounts of sunlight due to the tilt of Earth’s axis and revolution around the sun.
Very cold winters (Northern Hemisphere), Warm/hot summers

11. Factors Affecting Temperature
4. Altitude
The height into the atmosphere, away from sea level (0 m)
Temperature decreases 3F every 1000 ft (333 m) in elevation

12. Why is it colder the higher up you go if hot air rises?
Density of the air molecules decrease with elevation, more spread out,
therefore causing heat to be lost. As the air cools, molecules compact and
sink to where they encounter heat absorbed by solar radiation at the ground,
Temperatures increase and rise again – convection currents!

13. Factors Affecting Temperature
How much solar radiation is reflected back into space – Albedo

14. Albedo Effect 5. Clouds 6. Surface Color 7. Surface Texture
Thicker clouds, 70-95%
Thin clouds, 30-50%
6. Surface Color
Lighter colors
Snow %
Darker colors
Asphalt – 5-10%
7. Surface Texture
Rougher
Forests %
Smoother
Grass – 25-30%

15. Solar Radiation Reflection
What are two ways humans could help reduce the amount of solar radiation being absorbed?
Use lighter roofing materials instead of dark
Stop blacktopping roads, use brick, stone
or concrete instead

16. Temperature Maps
Maps that show areas of similar temperature – Isotherms
Can use color to identify areas of similar temperature
Can use lines to connect areas of similar temperature.

17. Air Pressure
Air pressure – the result of the weight of a column of air pushing down on an area.
Pulled down by the force of gravity.
Air pressure always moves from areas of high to areas of low:
The closer to Earth’s surface the higher the air pressure.
Sea level = greatest air pressure
The farther away from Earth’s surface, altitude or elevation, the lower the air pressure.
On top of a mountain = lowest air pressure.

18. Air Pressure What does air pressure indicate:
Low air pressure – BAD weather
Warmer air
Faster moving particles – high energy
Less dense
Carries lots of moisture
High air pressure - GOOD weather
Cooler air
Slower moving particles – less energy
More dense
Carries little moisture

20. Measuring Air Pressure
Mercury Barometer
Mercury adjusts to the
amount of pressure pushing
down on it.
As air pressure increases,
the mercury in the tube rises/high.
Sunny and Clear
As air pressure decreases,
the mercury in the tube falls/low.
Cloudy and Rainy

21. Measuring Air Pressure
2. Aneroid Barometer
Aneroid = “without liquid”
When air pressure increases, the walls push in, higher readings
Fair to Dry conditions
When air pressure decreases, the walls bulge out, lower readings
Stormy and Rainy
Measured in units called millibars (mb)
Low
High

22. Charting Air Pressure
Isobars – similar air pressure recordings connected by a solid line.
Low Pressure:
Cloudy and rainy
High Pressure:
Sunny and Clear
Close Lines:
Windy
Farther Apart Isobars:
Calm
Air Pressures move from regions of High to regions of Low L
Isobars H

23. Low High 4
Each isobar differs from the next isobar by ______ millibars.
The lowest air pressure reading on the map is _____ millibars.
What weather conditions would they most likely be experiencing?
The highest air pressure reading on the map is ______ millibars.
What pressure range is New York City located in?
992
Stormy
1016
Change

24. Where Does Weather Occur?
Weather takes place in the atmosphere.
The layer of gases that surround planet Earth.
Importance of the Atmosphere:
Make conditions on Earth suitable for living things.
Contains oxygen (O)and other gases.
Keeps Earth warm enough for liquid water to exist.
Protects organisms from radiation from the sun and meteoroids.

25. Composition of the Atmosphere
Argon & Carbon Dioxide – 1%
Made up of a mixture of gases:
Nitrogen – 78%
The most abundant gas
Oxygen – 21%
Argon - .93%
Carbon Dioxide %
Oxygen –
21%
Nitrogen – 78%

26. Layers of the Atmosphere
The atmosphere is divided
into 4 main layers based
on temperature and air
pressure changes.
Troposphere
Stratosphere
Mesosphere
Thermosphere

27. The Troposphere Closest to Earth’s surface. 0-16 km above sea level
Earth’s weather occurs here!
0-16 km above sea level
Contains almost all the mass of the atmosphere
As altitude increases, temperature decreases
1 km increase = 6.5C cooling.
At -60C it levels off.

28. The Stratosphere Extends from 16-50km above the earth’s surface
Increases in temperature as altitude increases due to the ozone layer.
Protective layer that absorbs the sun’s energy and converts it to heat.

29. The Mesosphere As altitude increases, temperature decreases.
The coldest layer at -90C
50-80km above the Earth‘s surface.
Protective layer where most meteoroids burn up.

30. The Thermosphere Extends from 80km to infinity – has no outer limit.
Divided into two different sections:
Ionosphere
aurora borealis
Exosphere
satellites orbit Earth.
The hottest layer at 1800C
due to heat coming in.

31. Aurora Borealis
A natural light display caused by the collision of energetic charged particles with atoms in the high altitude atmosphere