2 I. Moisture in the Atmosphere: the primary source of energy for the water cycle is the Sun. It unevenly heats Earth’s surface.A. Phases of the Water Cycle:1. Evaporation: liquid to gas. Requires energy making it a cooling process.2. Condensation: gas (water vapor) to a liquid. Releases energy into the air.
3 3. Transpiration: the releasing of water in the air by plants. 4. Precipitation: the falling of liquid or solid water from clouds.Ex. Rain, sleet, snow and hail.
4 B. Factors Affecting Evaporation Rate: 1. Temp.: as temp. inc. evap. rate inc.2. Humidity: as humidity inc. evap. rate decreases.3. Wind: as wind inc. evap. rate inc.4. Surface Area: as surface area inc. evap. rate increases.
5 C. Relative Humidity: a comparison between the amount of moisture in the air with the amount that the air can hold at that temp.Dewpoint Temp.: the temp. at which condensation occurs.* dew: drops of water forming on a cool surface.* frost: water vapor freezes (sublimates) on a frozen surface.
6 2. Sling Psychrometer: instrument used to determine the dewpoint temp 2. Sling Psychrometer: instrument used to determine the dewpoint temp. and relative humidity.3. Steps to determine Dewpoint:a. Find dry bulb temp.b. Find the diff. Between the wet and dry bulb temps.c. Use the chart on page 12 of the ref. Table.
7 D. Clouds: collection of tiny water droplets or ice crystals suspended in the atmosphere. 1. Cloud Formation:a. Warm moist air rises.b. Air cools below dewpoint temp. and droplets form around condensation nuclei (dust/salts).
8 2. Cloud Types:a. Cumulus: big puffy white clouds.b. Cirrus: whispy ice crystals high in the atmosphere.c. Stratus: low clouds that blanket the sky.
9 II. Air Pressure: the force/weight of air pushing on a surface II. Air Pressure: the force/weight of air pushing on a surface. Air pressure pushes in all directions equally. Pg. 13 ref. Table.A. Barometer: instrument used to measure air pressure.* As air pressure increases, the barometer rises.
10 B. Factors Affecting Air Pressure: 1. Temperature: as temp. increases, air pressure decreases.2. Altitude: as altitude increases, air pressure decreases.3. Humidity: as humidity increases, air pressure decreases.
11 C. Winds: caused by differences in air pressure C. Winds: caused by differences in air pressure. The greater the difference (gradient) the stronger the winds.1. Isobars: connect points of equal air pressure.*the closer the isobars the stronger the winds.
12 D. Local Breezes: smaller horizontal movement of air . 1. Sea breeze: air flows from the sea to the land.*cooler air (high pressure) over the sea, flows towards warmer air (low pressure) over the land.
13 2. Land breeze: air flows from the land to the sea. * Air over the land cools at night and flows towards the warmer air over the water.
14 E. Wind Direction: flow from regions of high to low pressure and named for the direction they come from.1. Cyclone: (low pressure) winds blow counterclockwise towards the middle.2. Anticyclone: (high pressure) winds blow clockwise and out.
15 F. Global Winds: caused by the unequal heating of earth’s surface F. Global Winds: caused by the unequal heating of earth’s surface. Page 14 ref. Table.1. Diverging zones: cool, dry high pressure air sinks at the poles and 300 lat.2. Converging zones: warm, moist low pressure air rises at the equator and 600 lat.
16 III. Air Masses: large masses of air that have a characteristic temp III. Air Masses: large masses of air that have a characteristic temp. and moisture of their source region. Page 13 ref. table.A. Source Regions:1. Maritime: formed over water. (moist)2. Continental: formed over land. (dry)3. Polar: cool air from high latitudes4. Tropical: warm air from low latitudes.
17 IV. Front: the boundary that separates two different air masses. Pg IV. Front: the boundary that separates two different air masses. Pg. 13 ref.A. Types of Fronts:1. Cold Front: dense cold air forces warm moist air upward creating heavy precipitation for short periods of time at the frontal boundary.
18 2. Warm Front: warm air slowly rises over cold air producing long periods of light precipitation ahead of the frontal boundary.
19 3. Occluded Front: a fast moving cold front over takes a slower warm front causing clouds and precipitation.
20 4. Stationary Front: cold and warm air masses near each other with neither advancing causing long periods of light precipitation.
21 B. Synoptic Weather Maps: show weather conditions on a national or global basis. 1. Storm Tracks: most storm systems move from west to east across the U.S.
22 V. Severe Weather:A. Hurricanes: a large rotating storm of tropical origin.*they get their energy from warm water. Once they hit land they lose energy.