# Tag Info

37

It's not a question of latitude but longitude and time zones. Prior to the advent of railway transportation the time set on clocks varied from towns within close proximity because the clocks were set to noon when the Sun was at its highest in the sky. This was more apparent for towns east and west of each other (ie different longitudes). When railway ...

29

Maybe a map will help visualise this a bit further: Source: "Solar time vs standard time" by Stefano Maggiolo - How much is time wrong around the world? As you can see, time zones are according to political boundaries, and this causes an offset from the official time to the solar time.

19

Time zones explain why you don't observe solar noon at 12:00 exactly, but not why the wall-clock time of solar noon varies with the seasons. In fact, even if you stay in place and don't observe DST, the time in the day where the sun is highest will vary throughout the year. The fixed stars rotate around the celestial pole with a very constant speed (with ...

16

The sun is really far away. Thus its rays are essentially parallel at the earth's orbit. So, while the diagram you posted is clearly a bit off in terms of the relative size and distance between the sun and the earth, the parallel rays are about right.

11

The sun is about 100 times the size of the Earth (in diameter), and the distance from the sun to Earth is about 100 times the diameter of the sun. Below is an image showing the sun, Earth, and the distance between them to scale. It looks at first like nothing more than a black bar. This image in the original is 4000 pixels (the limit of my Pixlr Editor) by ...

11

Primarily because of inertia. This phenomenon is called seasonal lag. It is true that the December solstice is the moment that the northern hemisphere gets the lowest total amount of insolation. Conversely, the June solstice corresponds to the moment of maximum insolation. The oceans, and to a lesser degree the land, absorb a lot of heat. Due to the ...

8

Henning Makholm's answer is excellent but omits the elegant definition of the mean Sun, which is what the clock at the Prime Meridian attempts to match: Consider a first fictitious Sun travelling along the ecliptic with a constant speed and coinciding with the true sun at the perigee and apogee (when the Earth is in perihelion and aphelion, respectively). ...

7

But if you scale up the Sun to it's real size compared to the Earth, Is pretty big. But then to be realistic in that manner you would also have to scale up the distance from the earth to the sun. But you don't have to even do that, as there is a much simpler way of seeing how large the sun is from the perspective of a position on the earth. Be on or very ...

7

Having the sun directly overhead can happen only between the Cancer and Capricorn tropics. That is, only the places between 23.5° of latitude north and 23.5° of latitude south. On the Cancer tropic (23.5° latitude north) it will happen once every year, on the day of the northern hemisphere solstice (about June 21st). On the Capricorn tropic (23.5° latitude ...

6

Given the known average distance to the Sun, and the radii of Sun and Earth, the basic trigonometry is simple. If the Earth and Sun were exactly the same size, and there was no atmospheric refraction, then exactly half the planet, or 180 degrees, would be illuminated. But since the Sun is so much bigger, again assuming no atmospheric refraction, then ...

5

As has been noted in a comment, it depends on how you define seasons (see https://earthscience.stackexchange.com/a/2603/111). If seasons are defined in astronomical terms, then they have the same length everywhere on the planet. This is simply down to geometry. However, the effects of astronomical seasons vary geographically in a number of ways. The ...

5

The rates at which plants consume CO$_2$ and animals consume O$_2$ is minuscule compared to the vast amounts of CO$_2$ and O$_2$ in the atmosphere. The amount of change overnight is not even measurable, unless the plants are in an enclosed structure. Interestingly, there is a variation in CO$_2$ concentraion over the course of a year as the Northern ...

5

Has the Earth had it's wobble that causes the seasonal variation in solar energy in the northern and southern hemispheres for it's entire history? First it depends on how you define the "entire history" of the earth. There was a pre-earth that was hit by a Mars sized body. The collision fragments ultimately collapsed into the present earth and moon. ...

5

Venice can't really be flooded by rivers, since there are none worth mentioning throughout the city. High tides are predictable, yes. Take a look at how Venice is situated. The historic city is sheltered behind low sandbanks/islands, which form the foremost coastline. Still the laguna is - obviously - connected to the open sea. Meaning: Huge waves, like in ...

5

If the winds subsided and the flooding was caused purely by tidal effects, which are astronomical events, shouldn't it have been predictable months, if not years in advance? The tides are only partially caused by astronomical events. There's always some difference between predicted and observed tide levels. The former typically only use astronomical ...

4

Well, kind of, depending on what you really mean. We're being rather vague with our terms, and so it shouldn't be surprising if the answer doesn't meet our expectations. We could interpret all these terms to conclude that such a situation will only rarely, or even never, happen. But allowing some reasonable latitude (pardon the pun) in our definitions, we ...

4

If we consider that by "Assume daily cycle and convection and so on operate as usual" you meant that all heat transport from/to the pole remain as it is today. Then, we can do a back of the envelope calculation. This calculation will at least give you an order-of-magnitude answer, and we can then consider everything that would affect the result. Currently ...

3

Cannot add to the excellent Time Zone, Daylight Savings, and Equation of Time (Mean Sun) explanations here, but I do want to mention something about the original question by Ian Paschal. It appears to be assumed that the high-point (culmination) and mid-point (transit) are the same, or that the point of highest altitude occurs on the celestial meridian. ...

3

Because no matter how big the Sun is compared to the Earth, only half the Earth can be facing the Sun at any given time. Try drawing a diagram where the Sun is much bigger with respect to the Earth. Make it ten times or a hundred times bigger or go all out and draw it to scale. Suppose it to be so big that it doesn't even look like a circle, but just a ...

3

Analogues to Mars Recurring Slope Linea (RSL) is a current study topic in Antarctica (Dry Valleys). On Earth, analogues are known as water tracks, which are linear zones of higher moisture along slopes in polar regions where water transit during snowmelt. This figure from Ward Hunt Island (NU, Canada) show well developed and typical water tracks. Source: ...

3

Dry season While not being very descriptive, 'dry season' is in general use, even for rainforests (Af Koppen climate, if you will). Example papers using the terminology here.

3

As JeopardyTempest commented: Actually, the astronomical seasons are defined in such a way that you should expect them to be a full 1 ½ months behind, not just 21 days! Namely, astronomical winter only starts at the winter solstice, astronomical spring only starts at the equinox etc.. A more intuitive definition would arguably be if the seasons were centered ...

3

Your photo doesn't show the strip of autumn-coloured trees very well; without your description I would have taken it for a strip of bare earth. All sorts of things could account for the autumn shades, there are too many unknowns to give a definite answer. We don't know whether the red-leaved trees are the same species as the others, for example. I ...

3

If the diameter of the Sun is $R_S$, the diameter of the Earth is $R_E$, and the orbital radius of the Earth is $r$, as in the drawing below (sorry about the quality), then you can do some geometry and compute $\theta$, which is the angle at which the light from the edge of the Sun's disk as seen from Earth is tangent to the Earth's surface referenced to a ...

2

This tool lets you determine daylight hours from latitude for any day of the year. I feel like this answer should be longer, but there is not much more to say.

2

In a short timescale, let's say one or two years after a permanent equinox state, the temperature would be basically the current mean annual temperature. This is because if we take the premise of keeping heat transport by convection (on the sea and the atmosphere) as it it today, the total energy inputs and outputs would be the same. Therefore, the same mean ...

2

You can try climatemps.com for easy access and plots. There they have a map you can click on or a list by countries. More data and analysis tools are available at the KNMI Climate Explorer, a more reliable and scientifically sound source. This is one of the outputs for Jakarta from jakarta.climatemps.com

2

You give the answer in your question when you say the earth is tilted (on its axis). Because of this tilt, in winter the northern hemisphere is tilted away from the sun, so for a short while the north pole experiences complete darkness, while at the south pole the sun is in the sky for 24 hours a day and it is summer. In the southern winter you have the ...

Only top voted, non community-wiki answers of a minimum length are eligible