Storm microclimates

Question 1

Where are lightning strikes in the UK mainly concentrated?

Answer 1

Coastal areas
Midlands, e.g. Sheffield, Newcastle
South east, e.g. Norfolk

Question 2

Why are thunderstorms more frequent in urban areas?

Answer 2

1. Urban heat island effect
   - causes atmospheric instability
   - warm air rises above urban areas, cools and condenses as rain
   - causes cloud cover to be greater in cities
2. Altering wind patterns
   - airflow obstructed by tall buildings
   - reduces ability for moist air to disperse
3. Aerosols and particulates
   - particles in air can cause water vapour to condense and form clouds
   - contributes to heightened cloud cover in cities

Question 3

What does this mean in terms of precipitation levels?

Answer 3

They are higher in urban areas compared to rural areas

Question 4

What happens to wind speed in urban areas?

Answer 4

Lowered, due to presence of tall buildings, which cause friction and act as a barrier to wind

Question 5

Cause and impact of turbulence?

Answer 5

Frictional drag
Forces air to be deflected and swirl like a vortex

Question 6

What is channelling?

Answer 6

Wind redirected down long straight canyon-like streets where there’s less friction
(Sometimes referred to as urban canyons)

Question 7

What is the Venturi effect?

Answer 7

Squeezing of wind into increasingly narrow gaps resulting in a pressure decrease and velocity increase