Weather Information Flashcards
What is the composition of the atmosphere?
- 78% nitrogen, 21% oxygen, 1% trace gases
What are the 4 distinct layers of the atmosphere?
- troposphere, stratosphere, mesosphere, and thermosphere
What is in the troposphere?
- contains the majority of weather, and goes up to around 20,000 feet
What is atmospheric stability?
- the resistance of the atmosphere to vertical movement
How can you determine the stability of the atmosphere?
- measuring the difference between the actual temperature lapse rate and the adiabatic rate (3C per 1,000 ft)
What are the conditions of an unstable atmosphere?
- cumuliform clouds, showery precipitation, turbulence, good visibility
What are the conditions of a stable atmosphere?
- stratiform clouds, continuous precipitation, smooth air, poor visibility in haze
How does wind form?
- air moving from areas of high pressure to areas of low pressure
In the Northern hemisphere, how does air flow around high-pressure areas?
- deflected to the right in a clockwise rotation
In the Northern hemisphere, how does air flow around low-pressure areas?
- deflected toward low pressure area in a counterclockwise rotation
What is wind shear?
- a sudden change in wind speed and/or direction
What is the most severe type of wind shear?
- micro burst
What are some indications that a microburst might be forming?
- intense rain shaft at the surface and a ring of blowing dust
How long do microbursts typically last?
- 5 to 15 minutes
What are isobars?
- lines of constant pressure
What are the 4 different types of front?
- warm, cold, stationary, and occluded
What type of weather can you expect from a warm front?
- widespread precipitation, low visibility, and rain
How does a warm front form?
- when a faster-moving body of warm air overtakes a slower-moving body of cold air, gradually pushing it out of the area
What type of weather can you expect from a cold front?
- cumulus clouds, squall lines, thunderstorms, and turbulence
How does a cold front form?
- when a mass of cold, dense, and stable advances and replaces a body of warmer, lighter air (snow plow)
What type of weather can you expect from a stationary front?
- a combination of cold front and warm front weather
How does a stationary front form?
- when 2 equally strong fronts meet
How does a cold-front occlusion form?
- cold air pushes underneath a warm air mass forcing it upwards
How does a warm-front occlusion form?
- warmer air overruns colder air mass
What are some key differences between cold fronts and warm fronts?
- cold fronts are much faster than warm fronts
- cold fronts have a steeper frontal slope
- cold fronts contain more violent weather
- cold front develop much faster
What are the 3 conditions necessary for the formation of a thunderstorm?
- water vapor, unstable lapse rate, and lifting force
What are the 3 stages of a thunderstorm?
- cumulus, mature, and dissipating
What type of weather can be seen during the cumulus stage of a thunderstorm?
- updrafts
What type of weather can be seen during the mature stage of a thunderstorm?
- updrafts, downdrafts, and precipitation
What type of weather can be seen during the mature stage of a thunderstorm?
- downdrafts
What are the 6 types of fog?
- radiation fog, advection fog, steam fog, upslope fog, precipitation fog, and freezing fog
What is radiation fog?
- forms on calm, cool nights when the ground cools and cools the surrounding air to its dew point
What is advection fog?
- when moist air moves over cold water or ground, most common along the coast
What is steam fog?
- when cold dry air moves over warm water
What is upslope fog?
- when moist stable air moves up sloping terrain
What is precipitation fog?
- when warm rain falls through cold air creating thick fog
What is freezing fog?
- when tiny water droplets freeze in the air when the temperature is 15F or below
