Associated with cumulus and cumulonimbus clouds ahead of the front in the warm air, producing showers and thunderstorms
Generally associated with stratus type clouds, overcast skies, fog and general rain or snow.

1. Why is the displacement of air (particles) important?
Warmth is transported during displacement
Moisture is transported during displacement
Clouds is transported during displacement
Waves are generated during displacement 2. Give the windlaw of Buys Ballot.
In 1857, Buys Ballots formulated a law identifying the relationship between wind and pressure distribution. The law states that if an observer stands having wind on his back, then in northern hemisphere to the left will be low pressure, on the right high pressure. Vice versa in southern hemisphere to the left will be high pressure, to the right lie low pressure.
3. How do we determine the windforce and direction on board of ships?
We can determine the windforce and direction by Visual contact with ocean state. It hard to determine the exact windforce and direction but the approximate data will be known. 4. Which forces determine the direction and force of wind?
Measuring of wind direction by means of wind vane
Measuring of wind speed by means of anemometer 5. Explain the gradient force
When a horizontal pressure gradient exists, a force, termed pressure gradient force, acts on the air which moves from high to low pressure at right angles to the isobars. 6. Explain the coriolis force.
It relates to the rotation of the earth about its axis, causes an air particle to be deflected to the right of its line motion in the northern hemisphere, and to the left line of its line of motion in the southern hemisphere. The force always acts at right angles to the line of motion particle. 7. In which direction bends the wind off due to coriolis force on the northern hemisphere?
It relates to the rotation of the earth about its axis, causes an air particle to be deflected to the right of its line motion in the northern hemisphere, and to the left line of its line of motion in the southern hemisphere. The force always acts at right angles to the line of motion particle. 8. When do we call a wind “geostrophical” ?
When isobars are straight lines parallel to each other, the resultant horizontal motion, due to the action of the pressure gradient and Coriolis force, is termed the geostrophic wind. Its direction is parallel to the isobars and its speed is constant. 9. Explain the friction force (for wind).
Friction force:
Close to the earth’s surface is “the friction layer” this layer depends on:
- composition of the atmosphere
- wind speed
- roughness of the terrain
• As a result of the friction the windspeed decreases
• If the speed decreases the coriolis force also decreases
• As a result the gradient force prevails 10. How high is the friction layer for land and for sea? 11. What is the effect of the friction force?
• As a result of the friction the windspeed decreases
• If the speed decreases the coriolis force also decreases
• As a result the gradient force prevails 12. Which force is needed for wind to follow curved isobars? 13. Which element determines the friction angle for wind? 14. What is an isallobar?
When isobars are straight lines parallel to each other, the resultant horizontal motion, due to the action of the pressure gradient and Coriolis force, is termed the geostrophic wind. Its direction is parallel to the isobars and its speed is constant. 15. What means veering of the wind? 16. What means backing of the wind? 17. B ← A When you are sailing with a ship from A to B, what will happen with; - theairpressure - the wind direction - the temperature - visibility 18. How do we call a front when cold air is overtaking warm air?
.Within a frontal depression the warm air usually ascends relative to cold air. This movement is marked by presence of active warm and cold fronts termed anafronts. On occasions the warm air may descend relative to the cold air, and a relatively inactive front termed a katafront exists, with limited low level stratiform cloud. 19. How do we call a front when warm air is overtaking cold air?
Within a frontal depression the warm air usually ascends relative to cold air. This movement is marked by presence of active warm and cold fronts termed anafronts. On occasions the warm air may descend relative to the cold air, and a relatively inactive front termed a katafront exists, with limited low level stratiform cloud. 20. What is sea wind?
The wind blowing in day time from sea, because of different heating of land and sea.
21. What is land wind?
22. In which direction does the wind flow with a cyclonic airsystem? (L) in the northern hemisphere?