69 terms

Natural Disasters Chapter 9

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Weather
Consists of the highly variable conditions in the atmosphere
Climate
The average period of weather over a long period of time
How many times greater is the Sun's energy on Earth than the heat flow from Earth's interior?
4000 times greater
Solar radiation
Energy received from the Sun
Percentage of visible light that comes from solar radiation
43%
Solar radiation vs Earth radiation
Short wavelength vs long wavelength
Percentage of Sun's energy reaching Earth's climate system
70%
Amount of solar energy equatorial area receives over polar regions
2.4 times
Major determinant of climate and weather all around the Earth
Circulation of the atmosphere and oceans
Why do polar latitudes receive less of the Sun's energy?
Solar radiation arrives at a low angle, causing much to be reflected
The greenhouse effect
Excess heat is radiated upward from Earth's surface at long wavelengths and gets absorbed by gases in the atmosphere, which in turn radiates the energy back down to Earth's surface
Albedo
Percentage of solar radiation that is reflected (Earth's albedo is 30%)
Common albedos
Clouds, snow, ice, water, ground, sand, grass, forest, cities
Albedo of black and white
Black=0 (absorbs everything)
White=1 (highly reflective)
Hydrologic cycle
Evaporated water rises convectively and then condenses and precipitates as snow and rain (24% of solar radiation used for this)
What has highest heat capacity?
Water (except for liquid ammonia NH3)
Specific heat
The amount of heat required to raise the temperature of a unit of mass by 1 degree Celsius
Convection
The transmission of heat in flowing water, air, or deforming rock
Conduction
The transmission of heat in a solid without the solid moving
Humidity
Amount of water vapor in the air
Relative humidity
Ratio of absolute humidity to saturation humidity
Saturation humidity
The maximum amount of water vapor that can exist in an air mass, and it increases with increasing temperature
Dew point temperature
When relative humidity reaches 100%, excess water vapor condenses and forms liquid water
Perceived temperature
Temperature and humidity combined
Latent heat
The stored energy in water when ice melts to water when supplied with 80 calories of heat per gram of ice
Latent heat of vaporization
The stored energy in water vapor when water evaporates to water vapor when it absorbs 540 calories per gram of water
Sublimation
Process of changing directly from solid to gas
Latent heat of condensation
Gives up the same amount of calories as were absorbed during evaporation
Latent heat of fusion
Water gives up the same amount of calories as were absorbed during melting
Adiabatic processes
Involve change in the temperature of mass without adding or subtracting heat caused by a change in pressure
A rising air mass encounters...
Lower pressure, expands, and cools
Lapse rate
Change in temperature over change in altitude
Dry adiabatic lapse rate
10 degrees Celsius per km of rise
Moist adiabatic lapse rate
5 degrees Celsius per km of rise
Lifting condensation level
Altitude where 100% humidity is reached
Land heat capability
Heats up quickly but loses heat quickly
Water heat capacity
Warms up more slowly but retains heat better
Monsoon
Moist air from above oceans warms as it moves over hot land and then rises and reaches colder levels in the atmosphere where it condenses and falls
Sensible heat
All energy generated by nuclear fission within Earth flows to the surface (convection and conduction)
Insolation
Amounts of heat that air and water receieve from solar radiation
Density of air as altitude rises
Decreases
Tropopause
The reversal where temperature of rising air switches from decreasing to increasing
Troposphere
Below the tropopause and ranges from 8-18 km in thickness
Stratosphere
Warmer air sits on top of cooler air (above troposphere)
Mesosphere
Temperature decreases upward (above stratosphere)
Atmosphere pressure at sea level
1013 millibars or 101.3 kilopascals
Mercury barometer
Measures temperature
Winds
Driven by pressure differences in the atmosphere
Pressure gradient force
Causes high pressure to push air toward low pressure
Isobars
Map lines defined by high and low pressure air cells
Coriolis effect
Created by Earth's rotation and deflects the path of large, moving bodies to the right in the Northern Hemisphere
Anticyclones
High-pressure air zones enclosed by roughly circular isobars
Cyclones
Low-pressure air zones enclosed by somewhat circular isobars
Hadley cells
Warm, moist equatorial air rises to high altitudes where it cools and drops its condensed moisture as abundant rain on the tropics
Intertropical convergence zone
Where the trade winds from the Northern and Southern hemispheres meet in the tropics
The Polar Cell
Thermal loop that occurs in high latitudes
Ferrel cell
Exists between the Hadley and Polar cells and is driven by those adjoining cells
Air masses
Large bodies of air that have little horizontal variation in moisture content and temperature
Fronts
Boundaries between different air masses
Jet streams
High-energy. elongated flows common in Earth's atmosphere and oceans
Most powerful and variable jet stream
Polar jet
Trough
A bend in the jet stream that is concave northward
Ridge
A bend in the jet stream that is convex northward
Major determinants of the paths of jet streams and hurricanes
Seasonal shifts of the Pacific and Bermuda highs and the Aleutian and Icelandic lows
What drives most surface circulation through ocean basins?
Winds
Density of water is increased by...
1. Lowering its temperature
2. Increasing its content of dissolved salts
Thermohaline flow
Deep-ocean waters flowing in an overturning circulation
Seawater density is increased...
1. At high latitudes, where water temperature is lowered
2. In the Arctic and Antarctic where freezing seawater forms pure ice but excludes salts into the remaining seawater
3. In warm climates where evaporation of water excludes salts into the remaining seawater
Atmospheric composition
Nitrogen (N2)= 78%
Oxygen (O2)= 21%