The Wind - When the wind blows!

Wind direction and wind speed records and charts for St Ives in Huntingdonshire & Cambridgehsire

 

Wind Gauges and Charts

Current Wind Direction

Current Wind Direction in St Ives, Huntingdonshire

Current Wind Direction in St Ives, Huntingdonshire

 

Current Wind Speed

Current Wind Speed in St Ives, Huntingdonshire

Current Wind Speed in St Ives, Huntingdonshire

 

Average Wind Speed

Average Wind Speed in St Ives, Huntingdonshire

Average Wind Speed in St Ives, Huntingdonshire

 

Today's Wind Run

Today's Wind Run at St Ives in Huntingdonshire

Today's Wind Run at St Ives in Huntingdonshire

 

Wind Gust Rate

The rate of change of the Wind Gust Speed at St Ives, Huntingdonshire

The rate of change of the Wind Gust Speed at St Ives, Huntingdonshire

 

Wind Chill

The Wind Chill Factor Temperature at St Ives, Huntingdonshire

The Wind Chill Factor Temperature at St Ives, Huntingdonshire

 

Wind Gust

The maximum recent recorded Wind Gust at St Ives, Huntingdonshire

The maximum recent recorded Wind Gust at St Ives, Huntingdonshire

 

72hr Wind Speed

Wind speed record over the alst 72 hours at St Ives, Huntingdonshire

Wind speed record over the alst 72 hours at St Ives, Huntingdonshire

 

Wind Gust Rate

An active graph of the maximum wind gust over the last 72 hours at the St Ives Weather Station

An active graph of the maximum wind gust over the last 72 hours at the St Ives Weather Station

 

Wind Gust Rate

An active graph of the wind direction over the last 72 hours at the St Ives Weather Station

An active graph of the wind direction over the last 72 hours at the St Ives Weather Station

 

Wind Gust Rate

An active graph of the average wind speed over the last hour at the St Ives Weather Station

An active graph of the average wind speed over the last hour at the St Ives Weather Station

 

Prevailing Wind

The chart on the right indicates the prevailing wind direction over the last seven (7) days. The higher the percentage figure the greater the number of hours that the wind blew from the given direction

The general prevailing wind in the United Kingdom is from the South West

 

Weekly Wind Direction

Cumulative chart showing the prevailing wind direction over the last 7 days at St Ives in Cambridgeshire

Cumulative chart showing the prevailing wind direction over the last 7 days at St Ives in Cambridgeshire

 

What is the Wind?

Where does the wind come from?

The definition of wind that we experience at ground level is the sum of complex movements of the atmosphere due to a number of different factors;

Spinning Earth

The revolution of the planet. The earth is a solid spinning ball surrounded by gas. Due to the effects of friction the rough ground surface of the planet, the ball, has a tendency to drag the atmosphere, the gas, along with it and cause it to rotate in the same general direction. However the rotational speed at the equator is faster than that nearer to the poles therefore this has the effect of creating an offset so winds in the northern hemisphere tend to move from the south-west towards the north-east and from the north-west towards the south-east in the southern hemisphere.

Heat from the Sun

Solar Radiation or heat. Everyone knows that hot air rises and cold air sinks. This has three major effects on the atmosphere;

    a) As the air at a given location is heated it rises causing the column of air to rise to a greater height than cooler air. Because a taller column weighs more than a shorter column this has the effect of creating a high pressure zone under warm air and a low pressure column under cold air. As nature wishes everything to be in equilibrium at ground level air moves from the high pressure zone to the low pressure zone creating another cause of atmospheric movement. b) The heating effect on the air, or the cooling for that matter, need not come directly from the sun but from contact with or radiation from other surfaces like the Sahara Dessert, the Arctic Ice Sheets or the rocks of the Himalayan mountains. The effect can also happen in coastal regions on the boundary between the land and the sea. The ability for land and sea to absorb, store and radiate of heat from the sun is different consequently during the day the air over the land tends to be hotter, whilst at night it is the other way around. This difference tends to cause on-shore breezes during the day and off-shore breezes at night. These movements are called Anabatic and Catabatic respectively and also relate to up slope and down slope movements of air in mountainous regions. c) The Squall. These are sudden increases in air movement, sometime but not always associated with a change of the direction of movement. They are caused by sudden cooling of the air as a result of precipitation, i.e.. rain, sleet or snow. Squalls can last for some period of time along a storm front, but as these fronts are themselves moving quite rapidly the squall to the stationery observer appears to last only a few minutes.

Land Form

The shape of the land or obstacles. In relation to the atmosphere as a whole we consider here only major obstacles such as mountain regions. Ignoring the local effects, described in 2b above, air movements created on a larger scale by 1 or 2a simply have to flow around or over them creating different effects known as Orographic wind movements.

It is the resultant sum of all these global movements of the atmosphere that we experience as wind. We must however be aware that there are local influences that will cause variation, sometime dramatic, to these more general movements. In the city high building, sky-scrapers, can create updrafts and downdrafts of air so severe that they can blow you right off your feet. Similarly if you are within a deep forest you may be completely oblivious to the fact that outside the trees there is a gale blowing.

The terminology used when describing the wind

Wind Speed and the Beaufort Scale

How far does the air move in a period of time the expression of which can thus take different forms;

  1. k.p.h. - Kilometres per hour.
  2. m.p.h. - Miles per hour.
  3. kts. - Knots or Nautical Miles per hour.

 

Before we had accurate instruments to measure velocity in 1805 Admiral Sir Francis Beaufort invented a method of categorising wind speed in a manner that could easily be understood by others

The Beaufort Scale for describing wind force

Force m.p.h. kts. Description Terrestrial Specification Nautical Specification
0 0-1 0-1

Calm

Calm, smoke rises vertical.

Sea surface like a mirror.

1 1-3 1-3

Light Air

Direction of wind shown by smoke drift, but not by wind vanes.

Ripples with the appearance of scales are formed, but without foam crests.

2 4-7 4-6

Light Breeze

Wind felt on face; leaves rustle; ordinary vanes moved by wind.

Small wavelets, still short, but more pronounced. Crests have a glassy appearance and do not break.

3 8-12 7-10

Gentle Breeze

Leaves and small twigs in constant motion; wind extends light flag.

Large wavelets. Crests begin to break. Foam of glassy appearance. Perhaps scattered white horses.

4 13-18 11-16

Moderate Breeze

Raises dust and loose paper; small branches are moved.

Small waves, becoming larger; fairly frequent white horses.

5 19-24 17-21

Fresh Breeze

Small trees in leaf begin to sway; crested wavelets form on inland waters.

Moderate waves, taking a more pronounced long form; many white horses are formed. Chance of some spray.

6 25-31 22-27

Strong Breeze

Large branches in motion; whistling heard in telegraph wires; umbrellas used with difficulty.

Large waves begin to form; the white foam crests are more extensive everywhere. Probably some spray.

7 32-38 28-33

Near Gale

Whole trees in motion; inconvenience felt when walking against the wind.

Sea heaps up and white foam from breaking waves begins to be blown in streaks along the direction of the wind.

8 39-46 34-40

Gale

Breaks twigs off trees; generally impedes progress.

Moderately high waves of greater length; edges of crests begin to break into spindrift. The foam is blown in well-marked streaks along the direction of the wind.

9 47-54 41-47

Severe Gale

Slight structural damage occurs (chimney-pots and slates removed).

High waves. Dense streaks of foam along the direction of the wind. Crests of waves begin to topple, tumble and roll over. Spray may affect visibility.

10 55-63 48-55

Storm

Seldom experienced inland; trees uprooted; considerable structural damage occurs.

Very high waves with long over-hanging crests. The resulting foam, in great patches, is blown in dense white streaks along the direction of the wind.  On the whole the surface of the sea takes on a white appearance. The 'tumbling' of the sea becomes heavy and shock-like. Visibility affected.

11 64-72 56-63

Violent Storm

Very rarely experienced inland; accompanied by wide-spread damage.

Exceptionally high waves (small and medium-size ships might be for a time lost to view behind the waves).  The sea is completely covered with long white patches of foam lying along the direction of the wind. Everywhere the edges  of the wave crests are blown into froth. Visibility affected.

12 73-83 64-71

Hurricane

Considerable damage and possible loss of life

The air is filled with foam and spray. Sea completely white with driving spray; visibility very seriously affected.

Gust

The air usually does not move with a constant velocity but its motion usually gently fluctuates however there are times when the velocity suddenly increases for  while and then falls back to previous levels. Where the wind speed increases by at least 10 m.p.h. for a period exceeding 20 seconds this is described as a "gust"

Cyclone and Anti-cyclone

Thee two terms are used to describe the motion of the wind. A cyclone is an area of low pressure around which winds blow counter-clockwise in the Northern Hemisphere and clockwise in the Southern Hemisphere. Also the term used for a hurricane in the Indian Ocean and in the Western Pacific Ocean. Where as an anti-cyclone is a large area of high pressure around which the winds blow clockwise in the Northern Hemisphere and counter-clockwise in the Southern Hemisphere.

Hurricane and Typhoon

A tropical storm in which the maximum sustained surface winds equal or exceed 64 knots (74 mph). These tropical cyclones are called hurricanes when located in the Northern Hemisphere. Everywhere else they are generally called typhoons or cyclones. The intensity of a hurricane is measured on the Saffir-Simpson Scale, which ranks hurricanes on a scale of 1 to 5 according to wind speed, barometric pressure, storm surge, and damage potential. Winds blow in a large spiral around a relatively calm centre of extremely low pressure known as the eye. Around the rim of the eye, winds may gust to more than 200 mph.

Tornado

A twisting, spinning funnel of low pressure air. The most unpredictable weather event, tornadoes are created during powerful thunderstorms. As a column of warm air rises, air rushes in at ground level and begins to spin. If the storm gathers energy, a twisting, spinning funnel develops. Because of the funnel's cloud and rain composition and the dust, soil, and debris it draws up, the funnel appears blackish in colour. The most energetic storms result in the funnel touching the ground. In these tornadoes, the roaring winds in the funnel can reach 300 mph, the strongest winds on Earth.

Wind Chill

The Wind Chill Temperature (Factor) is a calculation performed to estimate what the temperature really feels like. As humans and animals perspire the effect of moving air over their bodies evaporates the resultant perspiration making them feel cooler. Obviously the stronger the wind the greater the effect of wind chill.

Wind Run

In simple terms this is explained the distance the wind travels over a period of time or better still how far, horizontally, a balloon would travel if you let it go. Wind Run is calculated to provide the Daily, Monthly and Annual distances.

Never base important decisions on this or any weather information obtained from the Internet