Notes
Atmosphere and energy
- Layers: troposphere (weather), stratosphere (ozone), mesosphere, thermosphere. Air is 78% nitrogen and 21% oxygen.
- Heat moves by radiation, conduction and convection. The greenhouse effect keeps Earth warm. Albedo is reflectivity.
Pressure, wind and moisture
- Wind blows from high to low pressure and turns because of the Coriolis effect.
- Relative humidity $\displaystyle = \frac{\text{vapor present}}{\text{max vapor}} \times 100\%$. Clouds form when rising air cools to its dew point.
Fronts and storms
- Cold fronts: abrupt storms and cooling. Warm fronts: steady rain and warming.
- Hurricanes need warm ocean water; tornadoes are rated by damage (EF scale). Forecasts use satellites, radar and models.
Topics in this unit
Each topic has its own short notes and practice.
Practice
Ozone absorbs UV in the stratosphere.
Cooling air reaches saturation.
$15 \div 30 = 0.50$.
Dense cold air lifts warm air rapidly.
Sinking air suppresses cloud formation.
Their energy comes from warm water.
Free response
Write your answer first, then open the scoring guide.
Free-response question
Lightning flashes and thunder is heard 9 seconds later (sound speed 340 m/s). The air at your location holds 9 g of water vapor per cubic meter when it could hold 18 g. A cold front is approaching from the west.
(a) Calculate how far away the lightning is in meters and kilometers.
Show the answer and scoring guide
$9 \times 340 = 3060$ m, which is about 3.1 km.
Check off the points you earned:
(b) Calculate the relative humidity.
Show the answer and scoring guide
$\displaystyle \frac{9}{18} \times 100\% = 50\%$.
Check off the points you earned:
(c) Describe the weather changes expected as the cold front passes and explain why.
Show the answer and scoring guide
Cold, dense air pushes under warm air and forces it up quickly, forming cumulonimbus clouds, heavy rain or storms, then cooler, drier air and rising pressure.
Check off the points you earned: