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TIME ZONES OF THE UNITED STATES OF AMERICA
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[Knots] | [mph] | ||||
wind vanes still | |||||
Weather vanes being to move | No breaking |
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Light flags extended | Scattered whitecaps |
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Small tree branches move | Numerous whitecaps |
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Many whitecaps; Some spray |
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Whistling in wires | Whitecaps common; More spray |
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Resistance felt walking against wind | White foam streaks off breakers |
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Generally impedes forward progress | Edges of crests begin to break into spindrift; Foam blown in streaks |
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Slate (shingles) blow off roofs | Dense streaks of foam; Spray may reduce visibility |
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Trees broken or uprooted, "considerable structural damage" | Sea white with densely blown foam; Heavy rolling, lowered visibility |
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Accompanied by widespread damage. | Foam patches cover sea, visibility more reduced |
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Sea completely white with driving spray; Visibility greatly reduced |
0 | < 0.25 | < 15 | Minimal risk of damage to exposed utility systems; no alerts or advisories needed for crew; few outages. |
1 | 0.10-0.25 0.25-0.50 |
15-25 > 15 |
Some isolated or localized utility interruptions are possible, typically lasting only a few hours. Roads and bridges may become slick and hazardous. |
2 | 0.10-0.25 0.25-0.50 0.50-0.75 |
25-35 15-25 > 15 |
Scattered utility interruptions expected, typically lasting 12 to 24 hours. Roads and travel conditions may be extremely hazardous due to ice accumulation. |
3 | 0.10-0.25 0.25-0.50 0.50-0.75 0.75-1.00 |
≥ 35 25-35 15-25 > 15 |
Numerous utility interruptions with some damage to main feeder lines and equipment expected. Tree limb damage is excessive. Outages lasting 1-5 days. |
4 | 0.25-0.50 0.50-0.75 0.75-1.00 1.00-1.50 |
≥ 35 25-35 15-25 > 15 |
Prolonged and widespread utility interruptions with extensive damage to main distribution feeder lines and some high voltage transmission lines/structures. Outages lasting 5-10 days. |
5 | 0.50-0.75 0.75-1.00 1.00-1.50 > 1.50 |
≥ 35 ≥ 25 ≥ 15 Any |
Catastrophic damage to entire exposed utility systems, including both distribution and transmission networks. Outages could last several weeks in some areas. Shelters needed. |
Code Green 0-50 |
Good - Air quality is good | None |
Code Yellow 51-100 |
Moderate - Air quality becomes a concern for people with extra sensitivity to air pollution | People who are extra sensitive to air pollution should reschedule outdoor activities to when air quality improves |
Code Orange 101-150 |
Unhealthy for Sensitive Groups - Air quality is unhealthy for many people, especially those with lung disease, asthma, older adults, and children | Sensitive groups should cut back or reschedule strenuous outdoor activities |
Code Red 151-200 |
Unhealthy - Air quality is unhealthy for everyone, especially those with heart or lung disease | Everyone should avoid strenuous outdoor activities |
Code Purple 201-300 |
Very Unhealthy - Air quality is unhealthy for everyone, especially those with heart or lung disease | Everyone should avoid ANY physical outdoor activities |
Code Maroon 301-500 |
Hazardous - Air quality is hazardous for everyone | Everyone should avoid any outdoor activities at all costs |
1,2 | Low - You can safely stay outside without the risk of sunburn | No skin protection required |
3,4,5,6,7 | Medium - Seek shade during midday hours (1:00-4:00 PM) - Sunscreen and hat recommended | Skin protection required if prolonged exposure outdoors |
8,9,10,11+ | High to Extreme - Avoid being outdoors during midday hours (1:00-4:00 PM) - Sunscreen required, hat strongly recommended | Extra skin protection required |
Bortle Class | Color Key/Magnitude | Sky Description |
1 | Black / 7.6-8.0 | Excellent, naturally dark skies |
2 | Gray / 7.1-7.5 | Typical, truly dark skies - the Milky Way is clearly visible |
3 | Blue / 6.6-7.0 | Rural sky - Weak glow at the horizon above distant towns |
4 | Green / 6.1-6.5 | Rural/Suburban transition - Negative effect on stargazing |
5 | Yellow / 5.6-6.0 | Suburban sky - Strong negative effect on stargazing |
6 | Orange / 5.1-5.5 | Bright Suburban sky - Milky Way is invisible |
7 | Red / 4.6-5.0 | Suburban/Urban transition - Less than 100 stars visible to the naked eye |
8 | White / 4.1-4.5 | City sky - Less than 20 stars visible to the naked eye |
9 | White / 4.0 at best | Inner City sky - Entire night sky has a bright glow, only the brightest constellations are discernable |
Class | Peak Flux [W/m^2] | % Annual Flares | Earth Impacts |
B | I < 10^-6 | 37.77% | These and A-class flares are generally regarded as near-background levels. |
C | 10^-6 < I < 10^-5 | 59.23% | The most frequent flare classification - ten times as intense as B-class flares; these flares are relatively small with few noticeable consequences on Earth. |
M | 10^-5 < I < 10^-4 | 2.66% | Ten times as intense as C-class flares; medium-sized flares capable of causing brief radio blackouts or interference. Occasionally causes subsequent geomagnetic storms. |
X | I >= 10^-4 | 0.34% | The most intense solar flares; ten times as intense as M-class flares; capable of causing planet-wide radio blackouts and radiation storms. |
Meteor Shower Name | Pronunciation | Peak Nights | Mean Meteor Velocity | Best Viewed From |
Quadrantids | [kwa-DRAN-tids] | January 3-4 | 26 miles/sec [medium] | Northern Hemisphere |
Lyrids | [LIE-rids] | April 22-23 | 30 miles/sec [medium] | Northern Hemisphere |
Eta Aquariids | [EIGHT-a ACK-wah-rids] | May 6-7 | 42 miles/sec [swift] | Southern Hemisphere |
Alpha Capricornids | [AL-fa CAP-rih-CORN-ids] | July 27-28 | 15 miles/sec [slow] | Everywhere |
Delta Aquariids | [DEL-ta ACK-wah-rids] | July 28-29 | 26 miles/sec [medium] | Southern Hemisphere/Tropics |
Perseids | [PURR-see-ids] NOT "Per-sade" | August 12-13 | 37 miles/sec [swift] | Northern Hemisphere |
Orionids | [o-RYAN-ids] | October 21-22 | 41 miles/sec [swift] | Everywhere |
Southern Taurids | [southern TORR-ids] | October 23-24 | 17 miles/sec [slow] | Southern Hemisphere |
Northern Taurids | [northern TORR-ids] | November 11-12 | 18 miles/sec [medium] | Northern Hemisphere |
Leonids | [LEO-nids] | November 17-18 | 44 miles/sec [swift] | Everywhere |
Geminids | [JIM-o-nids] | December 13-14 | 22 miles/sec [medium] | Northern Hemisphere |
Ursids | [ER-sids] | December 21-22 | 20 miles/sec [medium] | Northern Hemisphere Only |
Hazard Level & Color Zone | ||
No Hazard (White Zone) | 0 | The likelihood of a collision is zero, or is so low as to be effectively zero. Also applies to small objects such as meteors and bodies that burn up in the atmosphere as well as infrequent meteorite falls that rarely cause damage. |
Normal (Green Zone) | 1 | A routine discovery in which a pass near the Earth is predicted that poses no unusual level of danger. Current calculations show the chance of collision is extremely unlikely with no cause for public attention or public concern. New telescopic observations very likely will lead to re-assignment to Level 0. |
Meriting Attention by Astronomers (Yellow Zone) | 2 | A discovery, which may become routine with expanded searches, of an object making a somewhat close but not highly unusual pass near the Earth. While meriting attention by astronomers, there is no cause for public attention or public concern as an actual collision is very unlikely. New telescopic observations very likely will lead to re-assignment to Level 0. |
Meriting Attention by Astronomers (Yellow Zone) | 3 | A close encounter, meriting attention by astronomers. Current calculations give a 1% or greater chance of collision capable of localized destruction. Most likely, new telescopic observations will lead to re-assignment to Level 0. Attention by public and by public officials is merited if the encounter is less than a decade away. |
Meriting Attention by Astronomers (Yellow Zone) | 4 | A close encounter, meriting attention by astronomers. Current calculations give a 1% or greater chance of collision capable of regional devastation. Most likely, new telescopic observations will lead to re-assignment to Level 0. Attention by public and by public officials is merited if the encounter is less than a decade away. |
Threatening (Orange Zone) | 5 | A close encounter posing a serious, but still uncertain threat of regional devastation. Critical attention by astronomers is needed to determine conclusively whether or not a collision will occur. If the encounter is less than a decade away, governmental contingency planning may be warranted. |
Threatening (Orange Zone) | 6 | A close encounter by a large object posing a serious but still uncertain threat of a global catastrophe. Critical attention by astronomers is needed to determine conclusively whether or not a collision will occur. If the encounter is less than three decades away, governmental contingency planning may be warranted. |
Threatening (Orange Zone) | 7 | A very close encounter by a large object, which if occurring this century, poses an unprecedented but still uncertain threat of a global catastrophe. For such a threat in this century, international contingency planning is warranted, especially to determine urgently and conclusively whether or not a collision will occur. |
Certain Collisions (Red Zone) | 8 | A collision is certain, capable of causing localized destruction for an impact over land or possibly a tsunami if close offshore. Such events occur on average between once per 50 years and once per several 1000 years. |
Certain Collisions (Red Zone) | 9 | A collision is certain, capable of causing unprecedented regional devastation for a land impact or the threat of a major tsunami for an ocean impact. Such events occur on average between once per 10,000 years and once per 100,000 years. |
Certain Collisions (Red Zone) | 10 | A collision is certain, capable of causing global climatic catastrophe that may threaten the future of civilization as we know it, whether impacting land or ocean. Such events occur on average once per 100,000 years, or less often. |
Magnitude | Damage | Frequency/Description |
< 2.0 | Mirco | ~8,000 per day/Not perceivable |
2.0-2.9 | Minor | ~1,000 per day/Generally not perceivable, but recorded |
3.0-3.9 | Minor | ~49,000 per year/Often felt, but cause no damage |
4.0-4.9 | Light | ~6,200 per year/Noticeable shaking of indoor items; significant damage unlikely |
5.0-5.9 | Moderate | ~800 per year/Can cause major damage to poorly constructed buildings over small regions; Slight damage possible to well-designed buildings |
6.0-6.9 | Strong | ~120 per year/Can be destructive in areas up to about 100 miles across in populated areas |
7.0-7.9 | Major | ~18 per year/Can cause serious damage over large areas |
8.0-8.9 | Massive | ~1 per year/Can cause severe damage in areas hundreds of miles across |
9.0-9.9 | Catastrophic | ~1 per year/Devastating and catastrophic damage in areas several thousand miles across |
10.0+ | Incredible (Unkown) | Never recorded/Widespread damage across very large areas (Unknown) |
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