Natural Disasters Midterm

Recurrence Interval

The average time interval between events of a certain size

Frequency

The chance an event of a certain size will occur within a given time period.

Risk

The frequency of an event multiplied by the expected cost incurred from the event

Assessment

Analysis of the possibility of a disaster

Mitigation

Activities to reduce the possibility or consequences of disasters

Prepardness

Planning and measures to prepare for the the impacts that cannot be mitigated

Response

Activities following a disaster

Recovery

To restore the affected area to its previous state

Infrastructure

The physical environment in which you live, and the various systems, services and regulations required for it to function

Natural Hazard

An earth process that is a potential threat to human life or property

Natural Disaster

A hazardous earth process that occurs over a limited period of time in a defined area and significantly affects people or property

Catastrophe

A hazardous Earth process that occurs over a

limited period of time in a defined area and significantly affects

people or property

Magnitude-Frequency Concept

Magnitude is inversely proportional to frequency

Lahar

Rapidly flowing volcanic debris which results from an eruption.

Evaporation

water that changes state from liquid to gas

Transpiration

evaporation of water through plants

Condensation

water that changes state from gas to a liquid

Precipitation

water that falls from the sky. Can be rain, snow or hail

Flood plain

A very wide, flat area that often forms near the exit of a river

Watershed

land area from which all water drains to a single point

Frequency Formula

F=1/RI

Bankful Stage

when the river cannot contain any additional water discharge

Thalweg

a line that connects the lowest point of a river along its path

Density Formula

D=M/V

Channelization

the process of clearing, straightening, or paving a stream channel

Hydrograph

A plot of flow rate versus time

Urbanization

Leads to increase in size and frequency of floods

Levees

Stream sediment that is deposited on the outside of the flood channel

Atmospheric Instability

Air rises due to density

Wind Shear

when wind from two different directions come together to create rotating winds

Latent Heat

the heat absorbed or released by a substance during a phase change

Dew Point

the temperature to which air must be cooled to become saturated with water vapor

Squall line

Line of thunderstorms that forms along a strong cold front

Severe Thunderstorm

Hail greater than 1-inch diameter, Winds over 58 mph, Tornadoes

Supercell

requires a wind shear

Derechos

powerful straight-line winds

Downburst

Sudden and strong downdraft

Fujita Scale

Used to measure tornadoes

Low pressure system

Associated with bad weather

High pressure system

Associated with good weather

Major hurricane

Magnitude of 3, 4, 5

Convergence

Rotation of the hurricane forces air into the center

Storm surge

Rise in water level due to hurricane

Coriolis Effect

the apparent curving path of a moving object caused by the Earth's rotation

Saffir-Simpson Scale

Used to measure hurricanes

Heat Index

what the atmosphere feels like when relative humidity is combined with air temperature

Heat Wave

prolonged period of excessively hot weather

Fire Triangle

Heat, Oxygen, Fuel

Types of Wildfires

Ground, Surface, Ladder, Crown