Weather Information Flashcards
Most of the Earth’s weather occurs in what region of the atmosphere? (
Most of the Earth’s weather occurs in the troposphere, which begins at the Earth’s surface and extends up to approximately 36,000 feet. As the gases in this layer decrease with height, the air becomes thinner and the temperature decreas1/s from about 15°C (59°F) t6 -56.5°C (-70°F).
What are the standard temperature and pressure values for sea level?
15 C (59) 29.92 (1013.2)
What are “isobars”?
An isobar is a line on a weather chart that connects areas of equal or constant barometric pressure.
If the isobars are relatively close together on a surface weather chart or a constant pressure chart, what information will this provide?
The spacing of isobars on these charts defines how steep or shallow a pressure gradient is. When isobars are spaced very close together, a steep pressure gradient exists, which indicates higher wind speeds. A shallow pressure gradient (isobars not close together) usually means wind speeds will be lower.
What does “dew point” mean?
Dew point is the temperature to which a sample of air must be cooled to attain the state of saturation.
When temperature and dew point are close together (within 5°F}, what type of weather is likely?
~isible m~i~ture in the form of clouds, dew, or fog. These are also ideal cond1t1ons for carburetor icing.
What factor primarily determines the type and vertical extent of clouds?
The stability of the atmosphere.
Explain the difference between a stable atmosphere and an unstable atmosphere. Why is the stability of the atmosphere important?
The stability of the atmosphere depends on its ability to resist vertical motion. A stable atmosphere makes vertical movement difficult, and small vertical disturbances dampen out and disappear. In an unstable atmosphere, small vertical air movements tend to become larger, resulting in turbulent airflow and convective activity. Instability can lead to significant turbulence, extens’ive vertical clouds, and severe weather.
How can you determine the stability of the atmosphere?
When temperature decreases uniformly and rapidly as you climb (approaching 3GC per 1,000 feet), you have an indication of unstable air.
If the temperature remains unchanged or decreases only slightly with altitude, the air tends to be stable.
When air near the surface is warm and moist, suspect instability.
List the effects of stable and unstable air on clouds, turbulence, precipitation and visibility.
State the general characteristics in regard to the flow of air around high-pressure and low-pressure systems in the Northern Hemisphere. (AC 00-6)
Low Pressure- inward, upward, and counterclockwise
High Pressure-outward, downward, and clockwise
What is a “trough”? (AC 00-6)
elongated area of relatively low atmospheric pressure .
a low or trough is an area of rising air.
Rising air is conducive to cloudiness and precipitation this brings bad weather.
What is a “ridge”? (AC 00-6)
Elongated area of high atmospheric pressure.
Descending air.
Good weather.
What is the primary means of obtaining a weather
briefing? (AIM 7-1-2, 7-1-4)
FSS. toll-free number (1-800-WX BRIEF).
What are some examples of other sources of weather
information? (AIM 7-1-2, 7-1-7, 7-1-8)
a. Telephone Information Briefing Service (TIBS) (FSS)
b. private industry sources.
c. The Direct User Access Terminal System (DUATS) and Lockheed Martin Flight Services (DUATSII).
d. In Alaska, Transcribed Weather Broadcast (TWEB) locations and telephone access to the TWEB (TEL-TWEB).
