1. Weather and Atmosphere

2. Weather Composed of Moisture Temperature Pressure
How these move through the atmosphere

3. Layers of the Atmosphere
Troposphere
Weather Occurs Here
Stratosphere
Ozone Layer
Mesosphere
Coldest Place in Atmosphere
Thermosphere
Hottest place in atmosphere

4. Why Is There Weather? Earth rotates Atmosphere contains water
Sun heats the Earth unevenly

5. Earth Rotates The Earth’s tilt changes the amount of sunshine
received through
the seasons
In June the northern
hemisphere is
tipped toward the
Sun, in December,
the southern does

7. Earth’s Atmosphere Contains Water Vapor
Water in our atmosphere undergoes
changes between liquid, solid and gas
phases as it is heated or cooled
The heating and cooling may come from
many sources, not just the Sun

8. Air Properties
Warm air is lighter and tends to move quicker than cold air
Warm air less dense than cold air
Buoyancy- less dense material moves to the top of denser material
Thermal expansion-when things get hot, expand and gases (air) gets lighter and moves upward, also how a thermometer works

9. Ascent and Descent Air rising cools Air descending warms
This causes an area of lower pressure
Air descending warms
This causes an area of higher pressure
Convection-warm gas rising, makes the wind

10. Why does air cool as it rises?
Pressures are lower as we rise higher in the
atmosphere
As air rises, it expands because it is moving
into an area of lower pressure.
Expansion takes energy, and so the rising
air gives up some of its thermal energy to
expand, and becomes cooler
The opposite applies to descending air

11. Wind movement

12. Sun Heats the Earth Unevenly
This is how temperature would look if there were no continents or oceans
Equatorial latitudes receive
more energy than Polar, and
are warmer
The Earth’s atmosphere
attempts to equalize the
temperature around the
globe by carrying warm air
north and cold air south,
and mixing them together
COLD
HOT
COLD

13. Sun Heats the Earth Unevenly
Land absorbs and releases energy faster than water or ice does

14. Earth Rotates As the air parcel moves southward, it is
deflected so much
that eventually It is
moving west. It
cannot reach the
equator.
Coriolis movement

15. Weather Zone Because the winds cannot flow directly
from the poles to the equator, cold air must
be carried in stages from north to south
The “stages” or cells are climatic zones
around the Earth
There are three cells between pole and
equator:
temperate zone
doldrums
tropics

16. The Earth’s Circulation Cells
At some
boundaries, air is
rising,others it
descends
Areas of ascent
form lows and
areas of descent
highs

17. Low Pressure
Caused when fronts meet and spin counter clockwise in the northern hemisphere
Think of a counter-top being low- counter clockwise
Air is rising, forms clouds
Weather- clouds and possible precipitation, strong winds, warmer temperatures

21. Low Pressure System

23. High Pressure Sinking air, moves clockwise in the northern hemisphere
Think of the clock which is up high-clockwise
Weather- weak winds, bright, clear, heavy dew or frost, temperature inversions and traps pollution

24. High Pressure System

27. Clouds A.k.a.- high fog, mist, haze
Forms when air cools below the dew point (water vapor condenses)
Shape- depends on air movement
Horizontal air- layered clouds
Vertical air- upward clouds
Temperature
Above freezing- rain
Below freezing- snow

28. Cloud Names Cirrus- thin, high, icy Stratus- sheets or layers
Cumulus- vertical and thick, fluffy
Alto- medium height
Nimbus- rain
Flat base of a cloud is the condensation level or dew point