Fog Flashcards
When does Fog occur?
When visibility is less than 1000 metres irrespective of whether the obscurity is produced naturally by water droplets, or by solid particles, largely from human activity
When does thick fog occur?
When visibility is less than 200 metres.
When does dense fog occur?
When visibility is less than 50 metres.
What can dense and thick fog be grouped as?
Natural Hazards
What is freezing food composed of?
Supercooled water droplets
What is rime?
Feathery crystals of ice
What industry is a large build up of rime dangerous too?
Electricity supply industry
Why is rime dangerous to the electricity supply industry?
It can bring down overhead wires
When does smog occur?
When air pollution ,largely from the burning of fossil fuels, provides additional particles which act as extra condensation nuclei for fog to form around.
Where is smog most commonly found?
Eastern Europe, China and India.
Why is smog not as common in Western Europe?
Due to the Clean Air Acts causing the development of smokeless zones between 1956-1960
What is photochemical fog the result of?
Photochemical reactions between the ultra-violet radiation from the sun and hydrocarbons and oxides of nitrogen.
What does photochemical fog look like?
A city covered with a dense, yellowish glare.
Why is photochemical smog a health hazard?
Irritates the eyes and throat and causes higher risk of asthma.
What season is radiation fog most common?
Winter due to long cool nights.
What type of areas are affected by radiation fog?
Inland areas, especially low lying basins, valleys, moist areas with high relative humidity in evenings.
How does radiation fog form?
Cooling due to radiation from the ground on clear nights when the wind is slight. Typically during anticyclones.
How is radiation fog dispersed?
By sunset radiation or by increased winds
What seasons does Advection fog occur in?
Winter or Spring