Meteorology and Weather
89 flashcards by MentisLibrary
Learn to read the sky: fronts, cloud types, pressure systems, and the storms they produce. Covers how forecasts are made, why they fail past a week, and the real difference between weather and climate.
- What is the difference between weather and climate?
- Weather is the state of the atmosphere over hours to days; climate is the statistical pattern over decades
- What are the main gases in dry air by volume?
- About 78 percent nitrogen, 21 percent oxygen, and just under 1 percent argon
- What are the layers of the atmosphere from the ground upward?
- Troposphere, stratosphere, mesosphere, thermosphere, and exosphere
- Which atmospheric layer contains nearly all weather?
- The troposphere
- Why does temperature increase with height in the stratosphere?
- Ozone absorbs ultraviolet radiation and warms the layer
- What is standard sea level atmospheric pressure?
- 1013.25 hectopascals, equal to 29.92 inches of mercury or 14.7 pounds per square inch
- Why does air pressure decrease with altitude?
- There is less atmosphere above to exert weight
- What is a low pressure system and what weather does it bring?
- A region of lower pressure where air converges and rises, generally bringing clouds and precipitation
- What is a high pressure system and what weather does it bring?
- A region of higher pressure where air sinks and diverges, generally bringing clear, settled weather
- Which way does air rotate around a low in the Northern Hemisphere?
- Counterclockwise and inward
- What is the pressure gradient force?
- The force pushing air from higher toward lower pressure, and the direct cause of wind
- What is the Coriolis effect?
- The apparent deflection of moving air caused by Earth's rotation
- What is geostrophic wind?
- Wind flowing parallel to straight isobars where the pressure gradient force and Coriolis effect balance
- How does surface friction change the wind?
- It slows the wind, which weakens the Coriolis effect and makes air cross isobars toward low pressure
- What is an isobar?
- A line on a weather map connecting points of equal atmospheric pressure
- What is an air mass?
- A large body of air with fairly uniform temperature and humidity, taking its character from its source region
- What is a weather front?
- The boundary between two air masses of different temperature and density
- What weather does a cold front bring?
- Rapidly rising warm air along a steep boundary, giving brief but intense showers or thunderstorms
- What weather does a warm front bring?
- Warm air gliding gently over cold air, giving long periods of light steady rain and lowering cloud
- What is an occluded front?
- A front formed when a faster cold front overtakes a warm front and lifts the warm air off the ground
- What is a stationary front?
- A boundary between air masses with little or no movement, often bringing prolonged cloud and rain
- What is a dryline?
- A boundary between moist and very dry air, common in the southern Great Plains
- What is relative humidity?
- The amount of water vapor in the air as a percentage of the maximum the air can hold at that temperature
- What is the dew point?
- The temperature to which air must be cooled at constant pressure to become saturated
- What is the difference between dew and frost?
- Dew condenses when a surface cools below the dew point; frost deposits directly as ice when that temperature is below freezing
- How does fog form by radiative cooling?
- The ground cools overnight, chilling the air above it to its dew point
- What is advection fog?
- Fog formed when warm moist air moves over a colder surface
- What are the four main cloud height groups?
- High, middle, low, and clouds with vertical development
- What do the Latin roots cirrus, cumulus, stratus, and nimbus mean?
- Curl of hair, heap, layer, and rain
- What are cirrus clouds made of and what do they indicate?
- Ice crystals, and they often signal an approaching warm front or change in weather