Weather Flashcards
The atmosphere is made up of what?
78 % Nitrogen, 21 % Oxygen, and 1% other
How high does the Troposphere extend?
Up to 20,000 feet over the northern and southern poles, 48,000 over the equatorial regions.
In the Troposphere what is the Temperature and pressure decrease rate?
Temp. 2 for every 1,000
Pres. 1 in. per 1,000 feet gained
Where is the tropopause?
Boundary layer above the troposphere.
How high is the stratosphere?
Above the Tropopause up to 160,000 feet.
What is standard level pressure and temp.?
29.92 and 15 degrees C.
What is the conditions for Low Level Wind Shear?
Directional wind changes of 180 degrees and speed changes of 50 knots or more.
What is a micro burst?
Occurs in a space of less than one mile horizontally and within 1,000 feet vertically. Life span of about 15 min. produce down drafts up to 6,000 per minute.
What is the dry adiabatic lapse rate? (unsaturated air)
3 degrees C per 1,000 feet
Moist Adiabatic lapse rate?
1.1 to 2.8 degrees C per 1,000 feet
What are the three states that water can be present in the atmosphere?
Liquid, Solid, Gaseous
What is humidity?
Refers to the amount of water vapor present in the atmosphere at a given time.
What is dew point?
Is the temperature at which the air can hold no more moisture.
What are the 4 methods that air can reach its saturation point?
- when warm air moves over a cold surface, the air temp. drops and reaches saturation.
- Cold air and warm air mix.
- Air cools at night through contact with the cooler ground
- air is lifted or is forced upward in the atmosphere
What is fog?
A cloud that begins within 50 feet of the surface.
Radiation Fog?
Ground cools rapidly and the surrounding air reaches saturation. If thicker than 20 feet is known as ground fog.
Advection Fog
Same as radiation fog, but with a wind up to 15 knots.
Up Slope Fog
When moist, stable air is forced up sloping land features like a mountain range.
Steam fog
Cold dry air, moves over warm water. Low level turbulence and icing are commonly associated with steam fog.
Ice Fog
Cold weather when the temp. is much below freezing and water vapor forms directly into crystals. Usually -25 degrees F or colder
What is needed for clouds to form?
Adequate water vapor and condensation nuclei, as well as a method by which air can be cooled.
What are cloud types determined by?
Height, Shape and Behavior.
They are classified by their height bases as what?
Low, Middle, High, as well as clouds with vertical development.
Low clouds
Earths surface up to 6,500 feet.
What three clouds are normally associated with Low clouds?
Stratus, Stratocumulus, and Nimbostratus, fog is also classified as low cloud.
Middle Clouds
6,500 feet to 20,000 feet
What clouds are included in Middle Clouds?
Altostratus and altocumulus
High Clouds
Above 20,000 feet and usually form in stable air
Types of high clouds
Cirrus, Cirrostratus and Cirrocumulus
What are the three stages of a thunderstorm?
Cumulus Stage, Mature Stage, Dissipating Stage
Cumulus Stage of a thunderstorm
Lifting action begins
Mature Stage
Reached within 15 mins. Most violent period in a thunderstorms life.
Dissipating Stage
Anvil-like shape begins the dissipating stage, downdrafts spread out and replace updrafts.
How many miles should you circumnavigate a thunderstorm?
20 miles.
What is visibility?
the greatest horizontal distance at which prominent objects can be viewed with the naked eye.
How is a drizzle classified?
Smaller than .02 inches in diameter.
Verga
Rain that falls through the atmosphere bur evaporates prior to striking the ground.
What are the four types of fronts?
Warm, Cold, Stationary, and Occluded
Warm Front
Warm mass of air advances and replaces a body of colder air. Move slowly 10 to 25 miles per hour. Precipitation is probable, poor visibility, Barometric pressure falls till front passes.
What happens during the passing of a warm front?
Stratiform clouds are visible and drizzle may be falling. Poor visibility, steady rise in temp.
After the passage of a warm front?
Stratocumulus clouds predominate and rain showers are possible.
Cold Front?
A mass of cold, dense and stable air advances and replaces a body of warmer air. Moves 25 to 30 MPH. So dense stays close to the ground. \
Prior to the passage of a cold front?
Cirriform or towering cumulus clouds, Cumulonimbus clouds are possible. Rains showers or haze. High Dew point.
During the passage of a cold front?
Towering cumulus or cumulonimbus clouds, Heavy rain showers with possibly of lightning/thunder and hail. Can possibly produce tornadoes. Poor visibility, winds variables and gusty, temp and dew point drop rapidly.
After Cold Front
Towering Cumulus and cumulonimbus clouds begin to dissipate. Good visibility, temps remain cool.
Occluded Front
Fast-moving cold front catches up with a slow-moving warm front.
What is a squall line?
A narrow band of thunderstorms
A tornado that does not reach the ground is what?
A funnel cloud
What are the two types of icing?
RIme and Clear Ice
