M5. Landslides and Soil Hazards

Atmospheric Processes

Contributes energy to the Earth and Largely to the atmosphere. Influences the weather and atmospheric conditions.

outgoing radiation

mostly of longer wavelengths and less energy (reflected infrared radiation (IR)). absorbed by the air generating more heat

incoming radiation

mostly of shorter wavelengths or shortwave electromagnetic (EM) radiation (ultraviolet and visible light)

Atmospheric Processes

movement/circulation of fluid driven by temperature differences ultimately causing heat transfer.

atmospherically

rising of warm air within low pressure area

atmospheric convection

due to uneven heating of the Earth; more heat is received at the equator

CONVERGENCE

movement of air mass towards low pressure area; cold air gets sucked into and converges at equator

DIVERGENCE

movement of air mass away from area of high pressure; cold dense air moves away from poles

CORIOLIS EFFECT

internally-driven Earth rotation causes moving objects to “turn” or “curve” a certain direction

CORIOLIS effect

negligible at equator and more pronounced farther away from the equator

Warmest air

found at the equator

coldest air

found at the poles

cyclonic winds

Convergence zones create low pressure areas because the warm air rises and denser, colder air gets sucked into it

anti cyclonic winds

Divergence zones create high pressure areas because the dense, cold air descends

Hadley cells

convection cells circulating upwards from the equator then down at midlatitudes

Polar cells

convection cells circulating upwards at high latitudes with descending air at poles

Ferrel cells

complex convection cells in between Hadley and Polar cells

Jet streams

narrow bands of high velocity winds at high altitudes: polar jets between Polar and Ferrel cells; and subtropical jets between Hadley and Ferrel cells

Prevailing Winds

the skewed directions of air flow in the convection belts.

Polar Easterlies

Prevailing Winds 1. and 2.

Westerlies

Prevailing Winds 3. and 4.

Trade Winds or Easterlies

Prevailing Winds 5. and 6.

doldrums

strip along equator where there is little to no wind) is more aptly termed Intertropical Convergence Zone (ITCZ). may shift N or S during summer; it deviates more to the N due to more land mass above the equator.

Fronts

occur at boundaries of two air masses with different densities, including temperature and humidity.

Polar front

where the warm air from a Ferrel cell meets with the cold air mass of a Polar cell.

Advection

part of the convection process and is generally the directional transfer of energy due to the bulk motion of a fluid.

Cold Front

the boundary along the leading edge of a cold air mass that is pushing out a warm air mass. As the cold front nears your region, the barometer falls. The cold air behind the front wedges under the warm air and lifts it sharply off the ground. Large cumulonimbus clouds appear. These clouds often bring thunderstorms and rain showers.

Type 1 cold fronts

those observed outside the zone of cyclonic activity and are generally slow moving which may even be quai-stationary in some case. defined by a general upglide of warm air over the entire frontal surface.

type 2 cold fronts

observed within the zone of cyclonic activity and as a rule move very rapidly. Warm air is lifted only along the leading edge of the intruding wedge of cold air.

Warm front

the boundary along a warm air mass that is pushing out a cold air mass. the warm air behind the front glides up and over the cold air. As a warm front approaches, high cirrus clouds appear. These are followed by stratus and nimbostratus clouds.

Occluded Front

forms when a cold front overtakes a slower-moving warm front. It is more complicated than the other because the two fronts interact.

Precipitation

occurs when the rain (or snow) droplets in the clouds grow by merging with other droplets. these droplets become heavy enough that the air currents can not hold them up anymore.

Rain

Frozen precipitation Melts and reaches the ground as.

Freezing Rain

Frozen precipitation melts in warm air. Rain falls and freezes on cold surfaces.

Sleet

Frozen precipitation melts in shallow warm air. Then refreezes into before reaching the surface.

Snow

falls through cold air and reaches the surface

Tropical Cyclones

warm core, non-frontal, rotating system of clouds (and thunderstorms) concentrated at it is center that form over sub/tropical waters.

Extratropical Cyclones

cold-core with spread out winds away from its center associated with fronts that can form over land or sea.

Tropical cyclones

develop their energy from the moisture/condensation which evaporated from the warm waters of the ocean and eventually die out after landfall

Cyclogenesis

The condensation of warm water vapor into liquid water releases heat (latent heat of condensation) into the atmosphere thereby causing warm air to expand horizontally or diverge. This process builds upon itself with increasing surface convergence towards low pressure center and release of latent heat.

Formative Stage

waves and shear lines of preexisting disturbances

Immature Stage

deepening, formation of lowest central pressure and reaching of max wind intensity; some cyclones may die out during this stage

Mature Stage

strength of winds and low pressure are sustained

Decaying Stage

dissipation of energy due to non-replenished moisture and increase in surface pressure over land

Wind Velocity

sustained speed of wind (for several mins) at the eyewall.

Gustiness

short-timed (in secs) wind speed

Movement Speed

speed at which the eye is moving across waters and land

Diameter

measured across outermost bands

Convective storms

typically associated with fronts and convection processes.

Thunderstorms and lightning

produced by rubbing of water droplets due to vertical winds (updrafts) that produces electrical fields.

Downbursts

powerful winds that suddenly descends and spreads laterally when it hits the ground.

Supercells

mesocyclones that are shortlived (an hour or so) resulting from rotating updraft.

Extreme temperatures or extreme climate events

odd and commonly unpredicted weather conditions based on a location’s recorded weather history

Heat index

qualifies the degree of apparent temperature perceived by people; high temp and high humidity result in high heat index

dry spells

heavily determined by El Niño caused by the El Niño - Southern Oscillation Cycle

El Niño

occurs when there are large-scale warmer temperatures of the Pacific Ocean than usual average.

La Niña

happen when the ocean temperatures are lower than usual average.

Natural Wildfires

unplanned fire that is caused by combustible vegetation; leading natural causes of combustion are dry climate, lightning, and volcanic eruption

Natural wildfires

typically uncontrolled and spread along forests due to wind and dry spells