chapter 8 weather air masses: definition air mass modification major air masses influencing...

Chapter 8 Weather Air Masses:

Definition

Air mass modification

Major air masses influencing conterminous USA  

Atmospheric Lifting Mechanisms 

Convergence: low pressure

Convection: heating

Orographic:

frontal: warm and cold front

Midlatitude Cyclonic Systems  

Air Masses

Figure 8.2

Atmospheric Lifting Mechanisms 

Figure 8.6

Dry and Moist Adiabatic Rise

Figure 8.7

Orographic Precipitation

Figure 8.9

Cold Front

Figure 8.11

Warm Front

Figure 8.13

Midlatitude Cyclone

Figure 8.14

1. Involves two air masses: mP and mT, they meet in the midlatitude, so the name.

2. Involves two atmospheric rising mechanisms: frontal (cold and warm) and low pressure

3. Cold front in moves faster and eventually catches the warm front (Occlusion)

Average and Actual Storm Tracks

Figure 8.16

Violent WeatherThunderstorms:

Upper Draft: Convective rise ( cumulus clods) by heat, thus more common in warm low latitude region.

Down Draft:  caused by rain/hail, very dangerous for airplane

Tornadoes Topography conducive to Tornadoes: smooth surface to roll the air Mesocyclone (~10km in diameter) to pick up the rolling air and turn it

vertical.

Tropical Cyclones: Tropical thunder storms, Easterly waves in trade wind or ITCZ

Sea surface temperature has to be 26oC 

Thunderstorms

Figure 8.19

Mesocyclone andTornado

Figure 8.22

Tornadoes

Figure 8.24

Easterly Wave

Figure 8.25

Tropical Cyclones

Figure 8.26

Hurricanes Gilbert and Catarina

Figure 8.26

The Hydrologic Cycle  

Soil-Water-Budget Concept  

Groundwater Resources  

Chapter 9 Water Resources

Hydrologic Cycle Model

Figure 9.1Round and round as it goes, the rivers never stop flowing and the oceans never overflow.

The flow of water linked the atmosphere, ocean, land, and living things through exchanges of energy and matter.

The Soil-Water Balance Equation

Figure 9.3

SRAETP

P: Precipitation which can in various forms such as rain, snow, hail, a complete list in Table 9.1.AET: Actual evapotranspiration (evaporation + transpiration)R: Runoff waterΔS: change in soil water

PET: The amount of water that would evaporate and transpire under optimum moisture condition, i.e. no shortage of water supply.

AET <= PET

Types of Soil Moisture

Figure 9.8

A block of soil is made up of three components, air, water, soil. The sum of the volume of air and water make up the total pore space in the soil.Volume Metric Soil Water = Vwater/(Vwater+Vair+Vsoil)Porosity=(Vwater+Vair)/(Vwater+Vair+Vsoil)

Soil-Moisture Availability

Figure 9.9

Surface Water Profile

Root zone

Capillary fringe layer

Ground water

Zone of Aeration:Part of the pore space is filled with air.

Water table

Zone of saturationAll pore space is filled with water

Capillary rise: liquid water rises through fine linear space

Groundwater Characteristics

Figure 9.17

Aquifer: a rock layer that is permeable to groundwater flow adequate for wells and springs. Confined: bounded above and below with impermeable layers, thus high water pressure and easy to extract. Unconfined: permeable layer on top and impermeable layers below, thus easily recharged from above, but need pump to draw water.

Groundwater Characteristics

Figure 9.17

Figures FS 9.2.1a, 9.2.3

Two Problems

1. Overdrawn. Due to demand for agricultural, industrial and urban use, groundwater table is decreasing .

2. Pollution: groundwater is recharged with surface water. Pollution of ground water will lead to pollution of groundwater, including, septic tank outflows, land fills, pestcides, herbcides, fertilizers, industrial waste injections etc.

point sources non-point sources

Water Withdrawal by Sector

Figure 9.21

Climate is weather over time, including both mean and variation

Climatic Classification Criteria

Factors influencing Climate

Chapter 10 Climate

Latitude: insolation

Land and Water: Marine and continental climate due to differences in heat capacity.

Geographic Position and Prevailing Winds: Places at the windward side of a continent with prevailing winds carrying maritime air mass have maritime climate.

Mountains and highlands: Mountains and highlands may prevent maritime air mass to reach inland. They force orographic rise and sequence moisture out of the air.

Ocean Currents: Warm currents (e.g. Gulf stream) warms air and cool currents chills the air.

Pressure and Wind Systems: The pressure “belts” and its seasonal shifting (e.g. ITCZ) influence precipitation.

Factors Controlling ClimateThe ultimate controller on climate is energy and water. Any factors influencing these two impact the climate. They include:

Classification criteria: temperature and precipitation and moisture efficiency for desert areas.

Tropical

Mesothermal

Microthermal

Polar

Highland

Desert

Climate Classification

Generalized Climate Regions

Figure 10.4

Uniformitarianism: An assumption that the same physical processes active in the environment today have been operating throughout geologic time.

Geologic time scale: Eons, Eras, Periods, Epochs

Radioactive dating: half time

Seismic tomography

Magnetic reversal

Continental drift

Sea floor spreading

Chapter 11 Dynamic Planet  

Geologic Time Scale

Figure 11.1

Earth age: 4.6 billion years condensed and congealed from a nebula of dust, gas and icy comets.

Scales of Geologic TimeEons: Eras: Periods: Epochs:

Zoic: lifeProtero-: former, anteriorPhanero-: visible to the naked eye flowering plantsPaleo-: oldMeso-: middleCeno-: recent

Earth’s Core :

Inner Core

Outer Core 

Earth’s Mantle:

Lower Mantle

Upper Mantle

Asthenosphere

Uppermost Mantle  

Crust  

Earth’s Structure and Internal Energy  

Scientists cannot dig that deep. The deepest hole scientists ever dug is 12.23km (20 years of effort!)

Scientists infer the deep Earth structure indirectly through seismic tomography. The rate of transmittance of seismic waves depends on the density of the structural material. Rigid matter transmits the seismic waves faster. Plastic zones simply do not transmit certain seismic waves. Some seismic waves are reflected when density changes, whereas others are refracted (or bent) as they travel through Earth.

How Scientists Know the Deep  Structure?

At least 90% of Earth’s Magnetism is generated by fluid outer core.

Magnetic North is at 83o N, 114oW in 2005. Magnetic north pole migrates. It moved 1100 km in the past century.

Magnetic reversal: Magnetic polarity sometimes fades to zero and returns to full strength with magnetic poles reversed. It happened 9 times in the past 4 million years. The transition period between reversal is relatively short (1,000 ~10,000 years)

Current records indicates that magnetic fields decay over the last 150 years. We may be within 1000 years of magnetic reversal.

Earth’s Magnetism

Isostatic Adjustment

Figure 11.4

Continental crust is lightest, “floating” on denser layers. When there is heavier loads, such as mountains, glaciers, , the crust “sink” deeper (like a boat loaded with cargo). Unloading these cargos will results in isostatic rebound as shown here.

GPS can be used to study the rate of isostatic rebound. A group of scientists from UAF found that southern Alaska is rebounding much faster than they thought because of melting of glaciers

The Geologic Cycle

Figure 11.5

Eight natural elements make up 99% of Earth’s crust! Oxygen and Silicon make up 74.3%. There are more Oxygen in the crust (47%) than in the atmosphere (21%) !

Crustal Movements: Sea Floor Spreading

Figure 11.13

A remarkable feature of the sea floor:

An interconnected worldwide mountain chain, forming a ridge ~64,000 km in length and ~1,000 km in width.

Magnetic Reversals

Figure 11.14

Evidence of sea floor spreading: 1. The magnetic particles orient themselves in line with the magnetic fields when the lava appeared and its orientation is frozen in the rocks. 2. Radioactive dating: the farther away from the ridge, the older the age of the rocks.

Relative Age of the Oceanic Crust

Figure 11.15

The oldest sea floor rock is 208 MBP (quite young compared to 4.6 Billion years of Earth).

Continents Adrift

Figure 11.16

7 major plates:

Three kinds of plate boundaries:ConvergentDivergent Transformative