Download Weather Notes I. Weather

Weather Notes
I.
Weather
II.
a. Meteorology- the study of the atmosphere
b. Humidity- A measure of the amount of water vapor in the air
c. Relative Humidity- the ratio of the amount of water vapor currently in the air at a given
temperature to the largest amount of water vapor the air can contain at that temp.
i.
Water vapor in air
Possible water vapor at that temp
ii. Ex. 50% relative humidity - means the water in the air is half the amount it could be
iii. Warm air can hold more water than cold air
d. As air rises it expands because of lower pressure
e. As air cools it slows down and begins to condense (water is polar)- occurs at the dew point
f. As the water droplets grow they fall as rain, sleet, hail or snow - precipitation
Air Behavior
III.
IV.
a. Upper regions of air are warmer than lower regions leads to a temperature inversion
Ex. Denver’s smog problem
Air rises as long as it is less dense than the air above it.
Air Masses- (fig 27.8)
a. Convectional lifting- warming air rises from “hot spots” followed by sinking cooler air ( lava
lamp)
b. Orographic lifting- air that is pushed up by a land mass
i. Warm dry air sinks on opposite side creating a rain shadow
c. Frontal lifting- (Figs. 27-11 and 27-12)
i. Front- the contact zone between two air masses
ii. Differences in temp., moisture and pressure cause movement of air masses
iii. Cold front- cold into warm air mass
iv. Warm front- warm into cold
Violent Weather
a. Thunderstormsi. Humid air rises cools and condenses
ii. Lightning1. falling water droplets bump into and rub against one another
2. cloud becomes electrically charged and release as lightning
iii. Thunder- lightning heats air up and it expands so fast it breaks the sound barrier
iv. Interesting Facts
1. ~1800 thunderstorms in progress in earth’s atmos.
2. lightning strikes ~100 times every sec.
3. Claims more than 200 people/ yr.
b. Tornadoes- funnel cloud that has touched the ground
c. Hurricanesi. Winds up to 300 km/hr.
ii. Caused by a long supply of warm, moist air