Glossary

Weather Glossary

Explore commonly used weather terms.

A

Absolute Humidity

Absolute humidity

Absolute humidity is the total amount of water vapor present in a given volume of air, expressed in grams per cubic meter.

Air humidity

Air humidity refers to the amount of water vapor present in the atmosphere, influencing weather patterns and comfort levels.

Air temperature

Air temperature is a measure of how hot or cold the air is, typically expressed in degrees Celsius (°C) or Fahrenheit (°F).

B

Buildup Index

Buildup index

The buildup index is the total amount of fuel available for consumption in the duff and larger fuels. It represents the cumulative effect of drying on these heavier fuel layers.

C

Celsius

The Celsius scale is a temperature measurement system where the freezing point of water is defined as 0°C, while the boiling point is 100°C under standard atmospheric pressure.

Climate models

Climate models are complex mathematical representations of the Earth's climate system, used to understand past climate patterns and predict future changes.

Cloudburst

A cloudburst is a very intense and localized rainfall event, typically occurring over a short period.

D

Dew point

The dew point is the temperature at which air, due to its humidity and temperature, becomes saturated and can no longer hold all its water vapor, resulting in condensation as dew, fog, or precipitation.

Drought Code

Drought code

The drought code is an index that represents the average moisture content of deep, compact, organic layers, and large logs. It indicates the long-term drying effects on heavier fuels.

Duff Moisture Code

Duff moisture code

The duff moisture code is a rating that shows the moisture level of the middle layer of decomposing material on the forest floor, and how likely it is for fires to smolder and burn deeper into the ground.

E

F

Fine Fuel Moisture Code

Fine fuel moisture code

The fine fuel moisture code is a numerical rating that indicates the moisture content of small, dead fuels like leaves, twigs, and litter, and from there, the relative ease of ignition and flammability of those fuels.

Fire Weather Index

Fire weather index

The fire weather index is a numerical rating of fire intensity based on weather conditions such as temperature, humidity, wind speed, and precipitation, used to assess wildfire risk.

G

Growing Degree Days

Growing degree days

Growing degree days is a measure of heat accumulation used to predict plant and insect development, calculated based on daily temperature thresholds.

H

Hadley Cells

Hadley cells

Hadley cells describe an atmospheric circulation of air near the equator where warm, humid air rises near the equator and moves toward the subtropics, where it descends as cooler, drier air where it starts moving back toward the equator.

Hurricane

A hurricane is a rotating tropical cyclone with sustained winds of at least 74 mph (119 km/h), a well-defined eye, and the potential to cause severe damage through strong winds, heavy rain, storm surges, and flooding.

I

Initial Spread Index

Initial spread index

The Initial Spread Index is a rating that combines the effects of wind and fine fuel moisture on the expected rate of the initial spread of fire shortly after ignition.

J

K

L

M

Microclimate

A microclimate is a small, localized atmospheric zone with distinct weather conditions differing from the surrounding climates, created by variations in topography, vegetation, bodies of water, or human-made structures.

N

O

P

Q

R

Relative Humidity

Relative humidity

Relative humidity is the ratio, expressed as a percentage, of the current amount of water vapor in the air to the maximum amount of water vapor the air can hold at that specific temperature and pressure.

S

T

Temperature Inversion

Temperature inversion

A temperature inversion happens when cooler air is trapped beneath warmer air, preventing the normal circulation of air.

Weather Glossary

A

Absolute Humidity

Absolute humidity

Air humidity

Air humidity

Air temperature

Air temperature

B

Buildup Index

Buildup index

C

Celsius

Celsius

Climate models

Climate models

Cloudburst

Cloudburst

D

Dew point

Dew point

Drought Code

Drought code

Duff Moisture Code

Duff moisture code

E

F

Fine Fuel Moisture Code

Fine fuel moisture code

Fire Weather Index

Fire weather index

G

Growing Degree Days

Growing degree days

H

Hadley Cells

Hadley cells

Hurricane

Hurricane

I

Initial Spread Index

Initial spread index

J

K

L

M

Microclimate

Microclimate

N

O

P

Q

R

Relative Humidity

Relative humidity

S

T

Temperature Inversion

Temperature inversion

U

V

W

X

Y

Z