Northerly winds tend to be gustier than southerly ones. Typically, gusts can be 60% higher than the mean speed, although in the middle of cities this can reach 100%. Gusts are higher inland than over the sea or windward coasts, although the mean wind speeds tend to be lower inland. There can be rapid variations in the speed of the wind - these are referred to as gusts. However, forecast winds are often given in miles per hour (where 1 knot is equivalent to 1.15 mph) or in terms of the Beaufort Scale. In the UK winds are measured in knots (nautical miles per hour). A specified height has to be used so that all the measurements taken across the world can be compared and because at ground level there are lots of obstacles like trees and buildings that can cause the wind to get stronger or weaker. Measurements of wind strength are made at 10 metres (33 feet) above the ground. For example, a westerly wind is blowing from the west towards the east. The direction given for the wind refers to the direction from which it comes. The movement of air around the earth from high pressure to low pressure is what brings about winds. Wind - generally makes the air feel cooler.North-facing slopes in the southern hemisphere and south-facing slopes in the northern hemisphere receive more sunlight than the opposite slopes and are warmer.This is because land heats up and cools down more quickly than the sea Distance from the sea - temperatures inland are usually higher than the coast during the summer and lower than the coast during winter.Altitude - getting colder as you go higher up.Latitude - warmer closer to the Equator and cooler moving away towards the poles.Temperature affects other weather elements including air pressure, wind, cloud formation, humidity and precipitation. Charts showing isobars are useful because they identify features such as anticyclones (areas of high pressure), depressions (areas of low pressure), troughs and ridges which are associated with particular kinds of weather. On a weather chart, lines joining places with equal sea-level pressures are called isobars. Weather can change on a daily basis especially at middle to high latitudes (parts of the earth that are quite far north or south of the Equator) where it is controlled by weather systems, depressions and anticyclones. All occlusions will cause a rise in pressure, a change in wind direction and precipitation will slowly clear when they have passed. Not all occlusions follow the same rules, as some will be more similar to warm fronts and some will be more like cold fronts, so some will cause it to feel warmer once it has passed, others cooler, some will lower the dew point, others will cause it to increase. On a synoptic chart an occluded front is a purple line with purple semi-circles and triangles. When a cold front catches up with a warm front, the warm air in the warm sector is forced up from the surface. An occlusion is formed when a cold front catches up with a warm front. These are more complex than cold or warm fronts. When the front has passed, the will be a steadying of the barometer (pressure will stop falling), a jump in temperature and dew point, a change of wind direction, and precipitation will stop, or mostly stop. Precipitation usually occurs in a wide belt about 400 km just ahead of the front. The semi-circles on the front point to which direction the front is moving.Īs a warm front approaches, temperature and dew-point within the cold air gradually rise and pressure falls more quickly. So warm air is replacing cold air at the surface. This is because the warm air is 'lighter' or less dense, than the colder air. The presence of a warm front means warm air is moving in and rising up over cold air.
On a synoptic chart a warm front is a red line with red semi-circles on it. This is the boundary between cold air and warm air and is when warm air replaces cold air at a point on the Earth's surface. Some cold fronts give only a shower at the front, while others give no precipitation. Rain occurs with most cold fronts and may extend some 100 to 200 km ahead of or behind the front. You can tell when a cold front has passed by a rise of pressure, a fall of temperature and dew point, and a change in wind direction.
The triangles on the front point to the direction that the front is moving. So cold air is replacing warm air at the surface. This is because the cold air is 'heavier' or denser, than the warmer air so sinks below it.
The presence of a cold front means cold air is moving in and pushing underneath warmer air. On a synoptic chart (a weather chart) a cold front is a blue line with blue triangles on it.
This is the boundary between warm air and cold air and is where cold air is replacing warm air at a point on the Earth's surface. There are three different types of weather front 1.
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